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.io.*;
public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int k=Integer.parseInt(str[3]);
        int ans=0;
        if(a>=k)
        {
            ans=k;
            k=0;
        }
        if(a<k)
        {
            ans+=a;
            k-=a;
        }
        if(k>0)
        {
            if(b>k)
            k=0;
            else
            k-=b;
        }
        if(k>0)
        ans-=k;
        pw.println(ans);
        pw.flush();
        pw.close();
    }
}