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: Accepted)

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		Set<Integer> set = new HashSet<>();
		int a,b,c,d,i,s =0;
		a=sc.nextInt();
		b=sc.nextInt();
		c=sc.nextInt();
		d=sc.nextInt();
		for(i=0;i<a;i++) {
			if(d == 0)break;
			d--;
			s++;
		}
		for(i=0;i<b;i++) {
			if(d == 0)break;
			d--;
		}
		for(i=0;i<c;i++) {
			if(d == 0)break;
			d--;
			s--;
		}
		System.out.println(s);
	}	
}