import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int K = s.nextInt();
        int A = s.nextInt();
        int B = s.nextInt();

        double A_div = A / K;
        double B_div = B / K;

        if (B_div - A_div >= 1 || A % K == 0 || B % K == 0) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
        s.close();
    }
}
/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