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: Accepted)


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main
{
	public static void main(String[] Arguments) throws IOException
	{
		BufferedReader BR = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer ST = new StringTokenizer(BR.readLine());
		int A = Integer.parseInt(ST.nextToken()), B = Integer.parseInt(ST.nextToken()), C = Integer.parseInt(ST.nextToken()), K = Integer.parseInt(ST.nextToken()), Sum = 0;
		Sum += Math.min(A, K);
		K -= Math.min(A, K);
		K -= Math.min(B, K);
		Sum -= Math.min(C, K);
		System.out.println(Sum);
	}
}