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)

function B167(_input) {
    var lines = _input.split("\n");
    var first = lines.shift().split(' ').map(v => v*1);
    var sum = 0;

    if (first[0] >= first[3]) {
        console.log(first[3]);
    } else {
        sum = first[0];
        first[3] -= first[0];

        if (first[1] >= first[3]) {
            console.log(sum);
        } else {
            first[3] -= first[1];
            sum -= first[3];
            console.log(sum);
        }
    }
}
B167(require("fs").readFileSync("/dev/stdin", "utf8"));