
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int k=scan.nextInt(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			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(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}



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

		Scanner scan = new Scanner(System.in);

		int k=scan.nextInt(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}



	} main {

		Scanner scan = new Scanner(System.in);

		int k=scan.nextInt(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			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 a=scan.nextInt() a scan.nextInt() scan.nextInt scan b=scan.nextInt(); b scan.nextInt() scan.nextInt scan int largest = (b / k) * k; largest (b / k) * k (b / k) b k k if(a <= largest) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} a <= largest a largest {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" {
			System.out.println("NG");
		} 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(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}



	}
} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int k=scan.nextInt(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			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(), a=scan.nextInt(), b=scan.nextInt();

		int largest = (b / k) * k;


		if(a <= largest) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}



	}
}
