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.Linq;
using System.Reflection.Metadata.Ecma335;

namespace ABC165_a
{
    class Program
    {
        static void Main(string[] args)
        {
            //整数入力
            long k = long.Parse(Console.ReadLine());

            //整数配列入力
            long[] vals = Console.ReadLine().Split(' ').Select(tmp => long.Parse(tmp)).ToArray();
            long a = vals[0];
            long b = vals[1];

            long k_max = b / k * k;
                        
            if (k_max >= a){
                Console.WriteLine("OK");
            }   else {
                Console.WriteLine("NG");
            }
        }
    }
}