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 C++ (Clang 10.0.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <string>
#include <math.h>
#include <iomanip>
using namespace std;

#define PI 3.14159265358979323846264338327950L

int res;

int main()
{
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int A, B, C, K;
    cin >> A >> B >> C >> K;
    if (K <= A)
    {
        res =  A;
    }
    else
    {
        if (K - A <= B)
        {
            res = A;
        }
        else
        {
            res =  A + 0 * (K - A) + (-1) * (K - A - B);
        }
    }
    cout << res << endl;
}