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: Wrong Answer)

import java.util.Scanner;

class Main{
  public static void main(String args[]){
    Scanner scan;
    int A;
    int B;
    int C;
    int K;
    int Aa;
    int Bb;

    scan = new Scanner(System.in);
    A = scan.nextInt();
    B = scan.nextInt();
    C = scan.nextInt();
    K = scan.nextInt();

    if (K >= A){
        Aa = A;
        K = K - Aa;
        if (K == 0){
            System.out.println (1*Aa);
        }else{
            if ( K >= B){
                Bb = B;
                K = K - Bb;
                if (K == 0){
                    System.out.println(1*Aa + 0*Bb);
                }
            }
        }
    }
    }
}