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: Accepted)

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Dynamic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;

namespace atcorder
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] intArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
            int A = intArray[0];
            int B = intArray[1];
            int C = intArray[2];
            int K = intArray[3];
            if(A >= K)
            {
                Console.WriteLine(K);
            }
            else if(A + B >= K)
            {
                Console.WriteLine(A);
            }
            else
            {
                Console.WriteLine(A - (K - (A + B)));
            }
        }
    }
}


//文字配列の取得
//string[] strArray = Console.ReadLine().Split(' ').ToArray();
//string S = strArray[0];
//string T = strArray[1];

//文字列の取得
//string s = Console.ReadLine();

//数字配列の取得
//int[] intArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
//int H = intArray[0];
//int W = intArray[1];

//数字の取得
//int N = int.Parse(Console.ReadLine());

//リスト型(int)の取得
//List<int> A = new List<int>(Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray());

//出力
//Console.WriteLine(ans);
//Console.WriteLine("Yes");
//Console.WriteLine("No");
//Console.WriteLine(cnt);