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: Accepted)

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

namespace atcoder_ensyuu_165_a
{
    class Program
    {
        private static void Main(string[] args)
        {

            int multiple = int.Parse(Console.ReadLine());
            int [] score = GetConsole();

            if (multiple < 1 || multiple > 1000)
            {
                Console.WriteLine("error");
                return;
            }

            if(score[0] < 1 || score[0] > score[1] || score[1] > 1000)
            {
                Console.WriteLine("error");
                return;
            }

            if ((score[1] - score[0]) >= (score[1] % multiple))
            {
                Console.WriteLine("OK");
            }
            else
            {
                Console.WriteLine("NG");
            }
        }

        private static int[] GetConsole()
        {
            return Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        }
    }
}