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.*;
import java.lang.*;
import java.io.*;
public class Main
 { 
	
	public static void main (String[] args)
	 {
Scanner scan=new Scanner(System.in);

	    
	    int a=scan.nextInt();
	    int b=scan.nextInt();
	    int c=scan.nextInt();
	   int k=scan.nextInt();
	   int i=0;
	   int sum=0;
	   if(k>=a)
	  { sum+=a;
		  k=k-a;
	  }
	  else
	    {sum=k;
			k=0;
		}
		if(k>=b)
		k=k-b;
		else k=0;
		if(k>=c)
		sum=sum-c;
	    else sum=sum-k;
	   
	System.out.println(sum);
   
   }
	   
	 }