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 Main(input) {
  input = input.split(" ");
  const A = parseInt(input[0], 10);
  const B = parseInt(input[1], 10);
  const C = parseInt(input[2], 10);
  var K = parseInt(input[3], 10);

  var count = 0;
  if (A < K) {
    count += A;
    K -= A;
  } else {
    console.log(K);
    return;
  }

  if (B < K) {
    K -= B;
    count -= K;
    console.log(count);
    return;
  } else {
    console.log(A);
    return;
  }
}

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