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.util.*;
class Main{
    public static void main(String args[]){
        Scanner scanner = new Scanner(System.in);
        int plusOne = Integer.parseInt(scanner.next());
        int zero = Integer.parseInt(scanner.next());
	    int minusOne = Integer.parseInt(scanner.next());
      	int amount = Integer.parseInt(scanner.next());
		int ans = 0;
      for (int i=0; i<amount; i++) {
      	if (i < plusOne) {
        	ans = ans + 1;
        } else if (i < plusOne + zero) {
        	ans = ans;
        } else {
        	ans = ans - 1;
        }
      }

      System.out.println(ans);

    }
}