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: Accepted)

#include <stdio.h>

int main() {
    int A,B,C,K,num,l=0,m=0;
    scanf("%d%d%d%d",&A,&B,&C,&K);
    if (A>=K) {
        num=1*K;
    }else{
        num=1*A;
        l=K-A;
    }
    if (B>=l) {
        num=num+0*K;
    }else{
        num=num+0*B;
        m=l-B;
    }
    num=num-1*m;
    printf("%d",num);
}