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){
    const arr = input.split(' ').map(Number);
    let K = arr[3];
    let total=0;
 
    if(K>=arr[0]){
        total += arr[0];
        K -= arr[0];
    } else {
        total += K;
        console.log(total);
        return;
    }
    K -= arr[1];    
    console.log(K>0 ? total-K:total)
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));