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>
//#include "./libb/lib.hpp"

using namespace std;
const uint64_t MOD = 1000000007;
const double PI = acos(-1);

int main()
{
    uint64_t aa;
    uint64_t bb;
    uint64_t cc;
    uint64_t kk;
    int64_t sum = 0;

    cin >> aa >> bb >> cc >> kk;

    if(aa >= kk){
        cout << aa << endl;
        //cout << "aa out " << endl;
        return 0;
    }

    //cout << "sum" << sum << endl;
    sum = aa;
    kk -= aa;

    if(bb >= kk){
        cout << sum << endl;
        //cout << "bb out " << endl;
        return 0;
    }

   // cout  << "sum" << sum << endl;
    kk -= bb;

    sum -= kk;
    cout << sum << endl;
    return 0;
}