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;

namespace BoxAndBall {
    class Program {
        static void Main(string[] args) {
            int N, M, A = 0;
            string[] str = Console.ReadLine().Split(' ');
            N = int.Parse(str[0]);
            M = int.Parse(str[1]);
            int[,] ball = new int[N,2];
            for (int i = 0; i < N; i++) {
                ball[i,0] = 1;
                ball[i, 1] = 0;
            }
            ball[0, 1] = 1;
            for (int i = 0; i < M; i++) {
                string[] tmp = Console.ReadLine().Split(' ');
                var a = int.Parse(tmp[0]);
                var b = int.Parse(tmp[1]);
                if (ball[a - 1, 1] == 1) {
                    ball[b - 1, 1] = 1;
                }
                ball[a-1,0]--;
                ball[b-1,0]++;
                if (ball[a - 1, 0] < 1) {
                    ball[a - 1, 1] = 0;
                }
            }
            for(int i = 0; i < N; i++) {
                Console.WriteLine(i+":"+ball[i,1]);
                if (ball[i, 1] == 1)
                    A++;
            }
            Console.WriteLine(A);
        }
    }
}