
import java.util.*;
import java.io.*;

import static java.lang.Character.isUpperCase;

public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        int K  =  in.nextInt();
        int A  =  in.nextInt();
        int B  =  in.nextInt();

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    }





/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz