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)

/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;



/* Name of the class has to be "Main" only if the class is public. */
public class Main
 
 
{
    static Scanner in = new Scanner(System.in);
    
    public static void solve()
    {
      int a =in.nextInt(),b=in.nextInt(),c=in.nextInt(),k=in.nextInt();
      
      if(a>=k)
      {
          System.out.println(k);
      }
      else if(a+b>=k)
      {
          System.out.println(a);
      }
      else
      {
          
          k=k-a-b;
          System.out.println(a-(k));
      }
    }
    

    
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		
		int t=1;
	//	in.nextLine();
		
		while(t>0)
		{
		    
		    solve();
		    t--;
		}
		
		
	
	//	System.out.println(x);
	}
}