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 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;
public class Main {
	public static void main(String atgs[]) {
		Scanner n = new Scanner(System.in);

		int A = n.nextInt();	//"1"の枚数
		int B = n.nextInt();	//"0"の枚数
		int C = n.nextInt();	//"-1"の枚数
		int K = n.nextInt();	//選び取る枚数

		int wa = 0;				//カードの数の和

		if(A + B >= K) {
			for(int i=0;i<A;i++) {
				wa += 1;
			}
			System.out.println(wa);

		}else{
			wa = A;
			K -= (A + B);
			for(int i=0;i<K;i++) {
				wa -= 1;
			}
			System.out.println(wa);
		}
	}
}