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.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class Main {

    public static void main(String[] args) throws Exception {

        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        ArrayList<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {
            mylist.add(strinput);
            strinput = reader.readLine();
        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int k = Integer.valueOf(arr01[3]);

        if (a >= k) {
            System.out.println(k);
        } else if (a + b >= k) {
            System.out.println(a);
        } else {
            int nokori = k - (a + b);
            System.out.println(a - Math.min(c, nokori));

        }

    }

}