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;

public class Main {

	static Main instance = new Main();

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		//入力値
		long A = scan.nextLong();
		long B = scan.nextLong();
		long C = scan.nextLong();
		long K = scan.nextLong();

		//WK変数
		long result = 0L;

		if (A + B >= K) {
			result = A;
		} else {
			result = A - (K - A - B);
		}

		//演算

		//結果出力
		System.out.println(result);
	}
}