import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	} main {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int k = sc.nextInt(); k sc.nextInt() sc.nextInt sc int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG") System.out.println System.out System System.out a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG" a / k != b / k a / k a k b / k b k "OK" a % k == 0 ? "OK" : "NG" a % k == 0 a % k a k 0 "OK" "NG" String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	}
} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();

		System.out.println( a / k != b / k ? "OK" : a % k == 0 ? "OK" : "NG");
	}
}