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(String[] args) {
        Scanner s=new Scanner(System.in);
        String line=s.nextLine();
        String[] SNum=line.split(" ");
        int[] num=new int[SNum.length];
        for(int i=0;i<SNum.length;i++){
            num[i]=Integer.parseInt(SNum[i]);
        }

        int sum;
        if(num[3]<=num[0]){
            sum=num[3];
        }else if(num[3]<=num[1]){
            sum=num[0];
        }else{
            sum=num[0]-(num[3]-num[0]-num[1]);
        }

        System.out.println(sum);
    }
}