diff --git a/src/components/PresentsPuzzle.tsx b/src/components/PresentsPuzzle.tsx
index e8f183a..5844ed5 100644
--- a/src/components/PresentsPuzzle.tsx
+++ b/src/components/PresentsPuzzle.tsx
@@ -2,6 +2,7 @@ import { useState, useRef } from 'react';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
+import { Slider } from '@/components/ui/slider';
 import SocialShare from './SocialShare';
 import { Gift, Play, RotateCw, Zap, Pause, ChevronRight, ChevronLeft, ChevronsRight, ChevronsLeft } from 'lucide-react';
 interface PresentsPuzzleProps {
@@ -17,6 +18,8 @@ const PresentsPuzzle = ({
   showSocialShare = false,
   shareUrl
 }: PresentsPuzzleProps) => {
+  const [numBoxes, setNumBoxes] = useState(100);
+  const [numPresents, setNumPresents] = useState(26);
   const [presentBoxes, setPresentBoxes] = useState<Set<number>>(new Set());
   const [aliceOpened, setAliceOpened] = useState<Set<number>>(new Set());
   const [bobOpened, setBobOpened] = useState<Set<number>>(new Set());
@@ -38,27 +41,27 @@ const PresentsPuzzle = ({
   // Generate random present positions
   const generatePresents = (): Set<number> => {
     const presents = new Set<number>();
-    while (presents.size < 26) {
-      presents.add(Math.floor(Math.random() * 100) + 1);
+    while (presents.size < numPresents) {
+      presents.add(Math.floor(Math.random() * numBoxes) + 1);
     }
     return presents;
   };
 
-  // Get Alice's opening order: 1, 2, 3, ..., 100
+  // Get Alice's opening order: 1, 2, 3, ..., numBoxes
   const getAliceOrder = (): number[] => {
     return Array.from({
-      length: 100
+      length: numBoxes
     }, (_, i) => i + 1);
   };
 
-  // Get Bob's opening order: 1, 3, 5, ..., 99, 2, 4, 6, ..., 100
+  // Get Bob's opening order: 1, 3, 5, ..., odds, 2, 4, 6, ..., evens
   const getBobOrder = (): number[] => {
     const odds = Array.from({
-      length: 50
-    }, (_, i) => i * 2 + 1);
+      length: Math.ceil(numBoxes / 2)
+    }, (_, i) => i * 2 + 1).filter(n => n <= numBoxes);
     const evens = Array.from({
-      length: 50
-    }, (_, i) => (i + 1) * 2);
+      length: Math.floor(numBoxes / 2)
+    }, (_, i) => (i + 1) * 2).filter(n => n <= numBoxes);
     return [...odds, ...evens];
   };
 
@@ -68,18 +71,18 @@ const PresentsPuzzle = ({
     const bobOrder = getBobOrder();
     let aliceCount = 0;
     let bobCount = 0;
-    for (let i = 0; i < 100; i++) {
+    for (let i = 0; i < numBoxes; i++) {
       const aliceFoundPresent = presents.has(aliceOrder[i]);
       const bobFoundPresent = presents.has(bobOrder[i]);
       if (aliceFoundPresent) aliceCount++;
       if (bobFoundPresent) bobCount++;
 
-      // Check if both reached 26 on the same turn (tie)
-      if (aliceCount === 26 && bobCount === 26) return 'tie';
+      // Check if both reached target on the same turn (tie)
+      if (aliceCount === numPresents && bobCount === numPresents) return 'tie';
 
       // Check individual winners
-      if (aliceCount === 26) return 'alice';
-      if (bobCount === 26) return 'bob';
+      if (aliceCount === numPresents) return 'alice';
+      if (bobCount === numPresents) return 'bob';
     }
     return 'tie'; // Default, though this should never happen
   };
@@ -117,11 +120,11 @@ const PresentsPuzzle = ({
       if (presents.has(aliceBox)) aliceCount++;
       if (presents.has(bobBox)) bobCount++;
 
-      if (aliceCount === 26 && bobCount === 26) {
+      if (aliceCount === numPresents && bobCount === numPresents) {
         currentWinner = 'tie';
-      } else if (aliceCount === 26) {
+      } else if (aliceCount === numPresents) {
         currentWinner = 'alice';
-      } else if (bobCount === 26) {
+      } else if (bobCount === numPresents) {
         currentWinner = 'bob';
       }
     }
@@ -160,7 +163,7 @@ const PresentsPuzzle = ({
       let bobCount = 0;
       let currentWinner: 'alice' | 'bob' | 'tie' | null = null;
       
-      for (let i = 0; i < 100 && !currentWinner; i++) {
+      for (let i = 0; i < numBoxes && !currentWinner; i++) {
         await new Promise(resolve => setTimeout(resolve, 50));
         
         // Check pause after delay, before opening boxes
@@ -192,11 +195,11 @@ const PresentsPuzzle = ({
         setBobFound(bobCount);
         setCurrentStep(i);
 
-        if (aliceCount === 26 && bobCount === 26) {
+        if (aliceCount === numPresents && bobCount === numPresents) {
           currentWinner = 'tie';
-        } else if (aliceCount === 26) {
+        } else if (aliceCount === numPresents) {
           currentWinner = 'alice';
-        } else if (bobCount === 26) {
+        } else if (bobCount === numPresents) {
           currentWinner = 'bob';
         }
       }
@@ -211,7 +214,7 @@ const PresentsPuzzle = ({
       let bobCount = bobFound;
       let currentWinner: 'alice' | 'bob' | 'tie' | null = winner;
       
-      for (let i = currentStep + 1; i < 100 && !currentWinner; i++) {
+      for (let i = currentStep + 1; i < numBoxes && !currentWinner; i++) {
         await new Promise(resolve => setTimeout(resolve, 50));
         
         // Check pause after delay, before opening boxes
@@ -243,11 +246,11 @@ const PresentsPuzzle = ({
         setBobFound(bobCount);
         setCurrentStep(i);
 
-        if (aliceCount === 26 && bobCount === 26) {
+        if (aliceCount === numPresents && bobCount === numPresents) {
           currentWinner = 'tie';
-        } else if (aliceCount === 26) {
+        } else if (aliceCount === numPresents) {
           currentWinner = 'alice';
-        } else if (bobCount === 26) {
+        } else if (bobCount === numPresents) {
           currentWinner = 'bob';
         }
       }
@@ -262,7 +265,7 @@ const PresentsPuzzle = ({
   };
 
   const stepNext = () => {
-    if (currentStep >= 99 || winner) return;
+    if (currentStep >= numBoxes - 1 || winner) return;
     updateStep(currentStep + 1);
   };
 
@@ -274,21 +277,21 @@ const PresentsPuzzle = ({
 
   const stepToEnd = () => {
     // Don't do anything if already at end or winner already determined
-    if (currentStep >= 99 || winner !== null) return;
+    if (currentStep >= numBoxes - 1 || winner !== null) return;
     
     const { presents, aliceOrder: aOrder, bobOrder: bOrder } = initializeSimulation();
     
     let aliceCount = 0;
     let bobCount = 0;
-    let winningStep = 99; // default to last step if no winner found
+    let winningStep = numBoxes - 1; // default to last step if no winner found
     
     // Find the step where someone first wins
-    for (let i = 0; i < 100; i++) {
+    for (let i = 0; i < numBoxes; i++) {
       if (presents.has(aOrder[i])) aliceCount++;
       if (presents.has(bOrder[i])) bobCount++;
       
       // Check if someone won on this step
-      if (aliceCount === 26 || bobCount === 26) {
+      if (aliceCount === numPresents || bobCount === numPresents) {
         winningStep = i;
         break;
       }
@@ -347,19 +350,20 @@ const PresentsPuzzle = ({
 
   // Render a grid of boxes
   const renderGrid = (title: string, openedBoxes: Set<number>, found: number, color: string) => {
+    const cols = Math.min(10, numBoxes);
     return <div className="space-y-3">
         <div className="flex items-center justify-between">
           <h3 className="font-semibold text-lg">
-            {title} <span className="text-sm text-muted-foreground">({openedBoxes.size}/100)</span>
+            {title} <span className="text-sm text-muted-foreground">({openedBoxes.size}/{numBoxes})</span>
           </h3>
           <Badge variant="secondary" className="text-sm">
             <Gift className="w-3 h-3 mr-1" />
-            {found}/26
+            {found}/{numPresents}
           </Badge>
         </div>
-        <div className="grid grid-cols-10 gap-1 p-2 bg-muted/30 rounded-lg">
+        <div className={`grid gap-1 p-2 bg-muted/30 rounded-lg`} style={{ gridTemplateColumns: `repeat(${cols}, minmax(0, 1fr))` }}>
           {Array.from({
-          length: 100
+          length: numBoxes
         }, (_, i) => i + 1).map(boxNum => {
           const hasPresent = presentBoxes.has(boxNum);
           const isOpened = openedBoxes.has(boxNum);
@@ -393,12 +397,42 @@ const PresentsPuzzle = ({
         <CardContent className="space-y-6">
           {/* Puzzle Statement */}
           <Card className="bg-muted/50">
-            <CardContent className="pt-6">
+            <CardContent className="pt-6 space-y-4">
               <p className="text-sm leading-relaxed">
-                Charlie puts <strong>26 presents</strong> in <strong>100 boxes</strong>, labeled 1 to 100.
+                Charlie puts{' '}
+                <span className="inline-flex items-center gap-2 font-semibold">
+                  <input 
+                    type="number" 
+                    value={numPresents} 
+                    onChange={(e) => {
+                      const val = Math.max(1, Math.min(numBoxes, parseInt(e.target.value) || 1));
+                      setNumPresents(val);
+                      resetSimulation();
+                    }}
+                    className="w-16 px-2 py-0.5 text-center border rounded bg-background"
+                    disabled={isRunning || currentStep > -1}
+                  />
+                  presents
+                </span>
+                {' '}in{' '}
+                <span className="inline-flex items-center gap-2 font-semibold">
+                  <input 
+                    type="number" 
+                    value={numBoxes} 
+                    onChange={(e) => {
+                      const val = Math.max(numPresents, parseInt(e.target.value) || numPresents);
+                      setNumBoxes(val);
+                      resetSimulation();
+                    }}
+                    className="w-16 px-2 py-0.5 text-center border rounded bg-background"
+                    disabled={isRunning || currentStep > -1}
+                  />
+                  boxes
+                </span>
+                , labeled 1 to {numBoxes}.
                 Each second, Alice and Bob look in one box. Alice opens them in order (1, 2, 3, …),
                 while Bob opens the odds first, then the evens (1, 3, 5, …, 2, 4, 6, …).
-                <strong> Who is more likely to see all 26 presents first?</strong>
+                <strong> Who is more likely to see all {numPresents} presents first?</strong>
               </p>
             </CardContent>
           </Card>
@@ -414,7 +448,7 @@ const PresentsPuzzle = ({
               <CardContent className="pt-6">
                 <div className="text-center">
                   <div className="text-2xl font-bold text-primary">
-                    {winner === 'tie' ? "🤝 It's a tie! Both found all 26 presents at the same time!" : `🎉 ${winner === 'alice' ? 'Alice' : 'Bob'} found all 26 presents first!`}
+                    {winner === 'tie' ? `🤝 It's a tie! Both found all ${numPresents} presents at the same time!` : `🎉 ${winner === 'alice' ? 'Alice' : 'Bob'} found all ${numPresents} presents first!`}
                   </div>
                 </div>
               </CardContent>
@@ -459,7 +493,7 @@ const PresentsPuzzle = ({
             </Button>
             <Button 
               onClick={stepNext} 
-              disabled={isRunning || currentStep >= 99 || winner !== null} 
+              disabled={isRunning || currentStep >= numBoxes - 1 || winner !== null} 
               variant="outline"
               className="gap-2"
               title="Step next"
@@ -468,7 +502,7 @@ const PresentsPuzzle = ({
             </Button>
             <Button 
               onClick={stepToEnd} 
-              disabled={isRunning || currentStep >= 99 || winner !== null} 
+              disabled={isRunning || currentStep >= numBoxes - 1 || winner !== null} 
               variant="outline"
               className="gap-2"
               title="Step to end"