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 <bits/stdc++.h>
#define FAST_IO ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define int long long int

using namespace std;

void code()
{
        int n;
        int s;
        int c;
        int z;
        cin>>n>>s>>c>>z;
        int nd=z-n,sd=nd-s,sum=0;
        if(nd<=0 || sd==0)
                cout<<z<<endl;
        if(sd>0)
        {sum+=(sd* -1);
         cout<<sum<<endl;}

}
signed main()

{
        FAST_IO;
        int t = 1;

        // cin>>t;

        while(t--)
        {
                code();
        }

        return 0;
}