Problem:
Score: 100 points

Problem Statement

Takahashi the Jumbo will practice golf.

His objective is to get a carry distance that is a multiple of K, while he can only make a carry distance of between A and B (inclusive).

If he can achieve the objective, print OK; if he cannot, print NG.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 1000

1 \leq K \leq 1000

Input

Input is given from Standard Input in the following format:

K
A B

Output

If he can achieve the objective, print OK; if he cannot, print NG.

Sample Input 1

7
500 600

Sample Output 1

OK

Among the multiples of 7, for example, 567 lies between 500 and 600.

Sample Input 2

4
5 7

Sample Output 2

NG

No multiple of 4 lies between 5 and 7.

Sample Input 3

1
11 11

Sample Output 3

OK

Solution in C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;
using System.Linq;

namespace ABC165A
{
    class Program
    {
        static void Main(string[] args)
        {
            int K = int.Parse(Console.ReadLine());
            int[] AB = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int A = AB[0];
            int B = AB[1];

            int num = K;
            bool ans = false;
            while (num <= B)
            {
                if (A <= num && num <= B) ans = true;
                num += K;
            }

            if (ans) Console.WriteLine("OK");
            else Console.WriteLine("NG");

            Console.ReadKey();
        }
    }
}