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.*;
public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);

      int a = sc.nextInt();
      int b = sc.nextInt();
      int c = sc.nextInt();
      int k = sc.nextInt();
      int sum = 0;
      
      if (a<=k) {
        for (int i=0; i<=a; i++) {
          if (b<=k-i) {
            for (int j=0; j<=b; j++) {
              int l=0;
              if (0<k-i-j) {
                l = k-i-j;
              }
              if (sum < i - l) {
                sum = i-l;
              }
            }
          } else {
            for (int j=0; j<=k-i; j++) {
              int l = 0;
              if (0<k-i-j) {
                l = k-i-j;
              }
              if (sum < i - l) {
                sum = i-l;
              }
            }
          }
        }
      } else {
        for (int i=0; i<=k; i++) {
          if (b<=k-i) {
            for (int j=0; j<=b; j++) {
              int l =0;
              if (0<k-i-j) {
                l = k-i-j;
              }
              if (sum <i-l) {
                sum = i-l;
              }
            }
          } else {
            for (int j=0; j<=k-i;j++) {
              int l =0;
              if (0<k-i-j) {
                l = k-i-j;
              }
              if (sum < i - l) {
                sum = i-l;
              }
            }
          }
        }
      }

      System.out.println(sum);
	}

}