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)

'use strict'

function main(input) {
    let a = Number(input.split('\n')[0].split(' ')[0]);
    let b = Number(input.split('\n')[0].split(' ')[1]);
    let c = Number(input.split('\n')[0].split(' ')[2]);
    let d = Number(input.split('\n')[0].split(' ')[3]);

    let sum = 0;
    let tmp;
    if (d-a>=0) {
        sum+=a;
        tmp=d-a;
        if (tmp-b>=0) {
            tmp=tmp-b;
            if (tmp-c>=0) {
                sum-=c;
            } else {
                sum-=tmp;
                console.log(sum);
                return;
            }
        }
    }
    console.log(sum);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));