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.Scanner;

public class Main {
    public static void main(final String args[]) {
        Scanner scan = new Scanner(System.in);
        int A = scan.nextInt();
        int B = scan.nextInt();
        int C = scan.nextInt();
        int K = scan.nextInt();
        int sum = 0;
        if(A >= K){
            sum = K;
        }else if(A < K){
            sum = A;
            K = K - A;
            if(B >= K){
                
            }else if(B < K){
                //sum = sum + B;
                K = K - B;
                if(C >= K){
                    sum = sum - K;
                }else{
                    sum = sum - C;
                }
            }
        }
        System.out.println(sum);
    }
}