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>
#include <string.h>

int main() {
    long long one, zr, mon, k, max = 0;
    
    scanf("%lld %lld %lld %lld", &one, &zr, &mon, &k);
    
    if (k - one <= 0){
        max = k;
        //printf("-\n");
    }
    else{
        if (k - (one + zr) >= k){
            max = one;
            //printf("--\n");
        }
        else{ 
            max = one - (k - (one + zr));
            //printf("---\n");
        }
    }
    
    printf("%lld\n", max);
    
    
    return 0;
}