Problem:
Problem Statement

You are given two integers a and b (a≤b). Determine if the product of the integers a, a+1, …, b is positive, negative or zero.

Constraints

a and b are integers.

-10^9≤a≤b≤10^9

Partial Score

In test cases worth 100 points, -10≤a≤b≤10.

Input

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

a b

Output

If the product is positive, print Positive. If it is negative, print Negative. If it is zero, print Zero.

Sample Input 1

1 3

Sample Output 1

Positive

1×2×3=6 is positive.

Sample Input 2

-3 -1

Sample Output 2

Negative

(-3)×(-2)×(-1)=-6 is negative.

Sample Input 3

-1 1

Sample Output 3

Zero

(-1)×0×1=0.

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

using System;
class Program
{
    static void Main(string[] args)
    {
        int ans = 0;
        // 整数の入力
        //int a = int.Parse(Console.ReadLine());
        // スペース区切りの整数の入力
        string[] input = Console.ReadLine().Split(' ');
        int N = int.Parse(input[0]);
        int M = int.Parse(input[1]);

        int[] arrB = { 0, 1, 1};
        Array.Resize(ref arrB, N+1);

        int[] arrR = { 0, 1, 0};
        Array.Resize(ref arrR, N+1);

        for (int i = 2; i <= N; i++)
        {
            arrB[i] = 1;
            arrR[i] = 0;
        }

        for (int i = 0; i < M; i++)
        {
            string[] input2 = Console.ReadLine().Split(' ');
            int x = int.Parse(input2[0]);
            int y = int.Parse(input2[1]);

            if (arrR[x] == 1)
            {
                if (arrB[x] == 1)
                {
                    arrR[x] = 0;
                    arrR[y] = 1;
                } else
                {
                    arrR[x] = 1;
                    arrR[y] = 1;
                }
            }
            arrB[x]--;
            arrB[y]++;
        }

        for (int i = 1; i <= N; i++)
        {
            ans += arrR[i];
        }

        // 文字列の入力
        string s = Console.ReadLine();
        //出力
        Console.WriteLine(ans);
    }
}