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)

const Main = input => {
    const inp = input.split(" ");
    const a = parseInt(inp[0], 10);//1
    const b = parseInt(inp[1], 10);//0
    const c = parseInt(inp[2], 10);//-1
    const k = parseInt(inp[3], 10);

    let result = 0;
    if(a + b >= k) {
        console.log(a);
    } else {
        console.log(a+b-c);
    }
}
 
Main(require("fs").readFileSync("/dev/stdin", "utf8"));