Problem:
Score : 200 points

Problem Statement

We have A cards, each of which has an integer 1 written on it. Similarly, we also have B cards with 0s and C cards with -1s.

We will pick up K among these cards. What is the maximum possible sum of the numbers written on the cards chosen?

Constraints

All values in input are integers.

0 \leq A, B, C

1 \leq K \leq A + B + C \leq 2 \times 10^9

Input

Input is given from Standard Input in the following format:

A B C K

Output

Print the maximum possible sum of the numbers written on the cards chosen.

Sample Input 1

2 1 1 3

Sample Output 1

2

Consider picking up two cards with 1s and one card with a 0.
In this case, the sum of the numbers written on the cards is 2, which is the maximum possible value.

Sample Input 2

1 2 3 4

Sample Output 2

0

Sample Input 3

2000000000 0 0 2000000000

Sample Output 3

2000000000

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

process.stdin.resume();
process.stdin.setEncoding('utf8');

var lines = []
var reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', (line) => {
  lines.push(line);
});

reader.on('close', () => {
 var abck = lines[0].split(' ');
 var a = Number(abck[0]);
 var b = Number(abck[1]);
 var c = Number(abck[2]);
 var k = Number(abck[3]);
 var ans = 0;
 

 var dis = (a+b+c) - k;

 while(true){
   if(c==0 || dis == 0){
     break;
   }
   c--;
   dis--;
 }

 if(dis !== 0){
   while(true){
     if(b==0 || dis == 0){
       break;
     }
     b--;
     dis--;
   }
 }
 
 if(dis !== 0){
   while(true){
     if(c==0 || dis == 0){
       break;
     }
     c--;
     dis--;
   }
 }

 
ans = a*1 + c*(-1);
console.log(ans);
 
 
 

 
 
 // for(i=0; i<k; i++){
 //   if(a !== 0){
 //     ans++;
 //     a--;
 //     continue;
 //   }
 //   if(b !== 0){
 //     b--;
 //     continue;
 //   }
 //   if(c !== 0){
 //     ans--;
 //     c--;
 //   }
 // }
 // 

});