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 (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main()
{

    int n[3], i, max = 0;
    int x[3] = {1, 0, -1};
    long k;

    for (i = 0; i < 4; i++)
    {
        if (i == 3)
        {
            scanf("%ld", &k);
        }
        else
            scanf("%d", &n[i]);
        max += n[i];
    }

    if (n[0] >= k)
        printf("%d", k);

    else if (n[0] + n[1] >= k)
    {
        printf("%d", n[0]);
    }
    else
    {
        printf("%d", n[0] + k - n[2] - n[1]);
    }
    return 0;
}