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: Wrong Answer)


using System;
using System.Linq;
using System.Xml.Schema;

class IDONTKNOWCSHARP
{
    public static void Main()
    {
        string[] values = GetLines();
        int value = 0;

        int A = int.Parse(values[0]);
        int B = int.Parse(values[1]);
        int C = int.Parse(values[2]);
        int K = int.Parse(values[3]);

        if (K - A > 0)
        {
            value += A;
            K -= A;

            if (K - B > 0)
            {
                K -= B;

                if (K - C > 0)
                {
                    //error
                }
                else
                {
                    value -= K;
                }
            }
            else
            {
                value += K;
            }
        }
        else
        {
            value += K;
        }

        Console.WriteLine(value);
    }

    static string[] GetLines()
    {
        return Console.ReadLine().Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries);
    }
}