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 {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner scan = new Scanner(System.in);
		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int K = scan.nextInt();
		int sumABC = A + B + C;
		int max = 0;

		if (sumABC <= K) {
			max = max + A;
			show(max);
		} else {
			max = A;
			if (A <= K) {
				K = K - (A + B);
				max = max - (C * K);
				show(max);
			}
		}
//		if (K <= A) {
//			max = max + (A * K);
//			show(max);
//
//		} else {
//			max = max + (A * K);
//			K = K - A;
//			if (K <= B) {
//				show(max);
//
//			} else {
//				max = max + (B * K);
//				K = K - B;
//				if (K <= C) {
//					max = max - (C * K);
//					show(max);
//				} else {
//					show(max);
//
//				}
//			}
//		}
	}

	private static void show(int max) {
		if (max <= 0) {
			System.out.print(0);
		} else {
			System.out.print(max);
		}
	}
}