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# (Mono-mcs 6.8.0.105) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


    class Program
    {
        static void Main(string[] args)
        {
            string[] Input = Console.ReadLine().Split(' ');
            long A = long.Parse(Input[0]);
            long B = long.Parse(Input[1]);
            long C = long.Parse(Input[2]);
            long K = long.Parse(Input[3]);
            long count = 0;
            
                if(K <= A){
                    count += K;
                }else{
                    if(K > A){
                    K -= A;
                    count += A;
                    }else if(K > B){
                        K -= B;
                    }else if(K > C){
                        K -= C;;
                    count -= C;
                    }
                }
                Console.WriteLine(count);
            
        }
    }