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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;

public class Main{

    Scanner sc = new Scanner(System.in);

    public static void main(String[] args){
        new Main().run();
    }

    void run() {

        long[] arr = new long[3];

        for (int i=0; i<3; i++) arr[i] = sc.nextLong();

        long k = sc.nextLong();

        long sum = 0;

        long[] cnt = new long[3];

        for (int i=0; i<3; i++) {
            if (arr[i] > k) {
                cnt[i] = k;
                k = 0;
            } else {
                cnt[i] = arr[i];
                k -= arr[i];
            }
        }

//        for (int i=0; i<3; i++) System.out.println(cnt[i]);

        System.out.println(cnt[0] - cnt[2]);



    }
}