Problem:
Score : 100 points

Problem Statement

Joisino wants to evaluate the formula "A op B".
Here, A and B are integers, and the binary operator op is either + or -.
Your task is to evaluate the formula instead of her.

Constraints

1≦A,B≦10^9

op is either + or -.

Input

The input is given from Standard Input in the following format:

A op B

Output

Evaluate the formula and print the result.

Sample Input 1

1 + 2

Sample Output 1

3

Since 1 + 2 = 3, the output should be 3.

Sample Input 2

5 - 7

Sample Output 2

-2

Solution in C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Linq;
class Program
{
	static void Main(string[] args)
	{
		int personNum = int.Parse(Console.ReadLine());
        string[] comments = Console.ReadLine().Split(' ');
        int[] absVals = new int[personNum];
        for(int i=0; i<personNum; i++){
            absVals[i] = int.Parse(comments[i]);
        }

        Array.Sort(absVals);

        bool isOdd = true;
        bool isError = false;
        if(personNum % 2 == 0){
            isOdd = false;
            if(comments.Contains("0")){
                isError = true;
            }
        }

        int loopFirst = 0;
        if(isOdd){
            loopFirst = 1;
        }
        int before = -1;
        bool first = true;
        for(int i=loopFirst; i<personNum; i++){
            if(first){
                if(absVals[i] == before){
                    isError = true;
                    break;
                }else{
                    before = absVals[i];
                }
                first = false;
            }else{
                if(absVals[i] != before){
                    isError = true;
                    break;
                }else{
                    before = absVals[i];
                }
                first = true;
            }
        }

        if(isError){
            Console.WriteLine("0");
        }else{
            if(isOdd){
                personNum--;
            }
            int result = (personNum/2) * (personNum/2);
            result = result % 1000000007;
            Console.WriteLine("" + result);
        }
        

	}
}