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.Abc
{
    // 問題:
    class A_165_We_Love_Golf
    {
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            // 整数の入力
            int k = int.Parse(Console.ReadLine());

            // 整数配列の入力
            var inputintArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();

            int a = inputintArray[0];
            int b = inputintArray[1];

            //for (int i = a; i < b + 1; i++)
            //{
            //    if (i % k == 0)
            //    {
            //        Console.WriteLine("OK");
            //        break;
            //    }
            //    else if (i == b)
            //    {
            //        Console.WriteLine("NG");
            //    }
            //}
            for (int i = 1; i < b + 1; i++)
            {
                int keisan = k * i;

                if (keisan >= a && keisan <= b)
                {
                    Console.WriteLine("OK");
                    break;
                }
                else if (i == b)
                {
                    Console.WriteLine("NG");
                }
            }

            Console.Out.Flush();
        }
    }
}