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# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;
using System.Linq;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] inputArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();

            int A = inputArray[0];
            int B = inputArray[1];
            int C = inputArray[2];
            int K = inputArray[3];
            int num = 0;
            for (int i = 0; i < K; i++)
            {
                if(A > i)
                {
                    num++;
                }
                else if(B > i)
                {
                    
                }
                else if(C > i)
                {
                    num--;
                }
            }
            Console.WriteLine(num);
            Console.ReadKey();
        }
    }
}