import java.util.Scanner;

public class Main {
    public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    }
} Main public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    } main {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int k = scan.nextInt(); k scan.nextInt() scan.nextInt scan int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int max = b / k; max b / k b k if (k * max >= a) {
            System.out.println("OK");
          	return;
        } k * max >= a k * max k max a {
            System.out.println("OK");
          	return;
        } System.out.println("OK") System.out.println System.out System System.out "OK" return; System.out.println("NG") System.out.println System.out System System.out "NG" String args[] args public class Main {
    public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    }
} public class Main {
    public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String args[]) {

        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();

        int max = b / k;

        if (k * max >= a) {
            System.out.println("OK");
          	return;
        }

        System.out.println("NG");
    }
}
