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: Accepted)

"use strict";

const main = (input) => {
    const spi = input.split('\n');
    let [a,b,c,k] = spi[0].split(' ').map(e => Number(e));

    let ans = 0;

    const ak = Math.min(a, k);
    ans = ak;
    k -= Math.min(a, ak);

    if (k > 0)
        k -= Math.min(b, Math.min(b, k));

    if (k > 0) {
        const ck = Math.min(c, k);
        ans -= ck;
    }

    console.log(ans);
};

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