
import java.util.Scanner;

public class Main {
    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        boolean flag = false;
        for(int i = a; i<=b; i++){
            if(i % k ==0){
                flag = true;
            }
        }

        System.out.println(flag?"OK":"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