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: Wrong Answer)

#include <iostream>
using namespace std;

int main(int argc, char *argv[])
{
  string As, Bs, Cs, Ks;
  cin >> As >> Bs >> Cs >> Ks;
  int A = stoi(As), B = stoi(Bs), C = stoi(Cs), K = stoi(Ks);

  if (A + B >= K)
  {
    cout << A << endl;
    return 0;
  }

  if (A + C >= K)
  {
    cout << A - C << endl;
  }

  if (A > C)
  {
    if (A > K)
    {
      int dff = K - A;
      cout << A - dff << endl;
    }
    else
    {
      cout << 0 << endl;
    }
  }
  else
  {
    cout << 0 << endl;
  }

  return 0;
}