import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			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) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} Main public static void main(String[] args) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	} main {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	} int k k a a b b x; x Scanner sc = new Scanner(System.in); sc new Scanner(System.in) k = Integer.parseInt(sc.next()) k Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc a = Integer.parseInt(sc.next()) a Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc b = Integer.parseInt(sc.next()) b Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc sc.close() sc.close sc x = (b / k) * k x (b / k) * k (b / k) b k k if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} a <= x a x {
			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) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} public class Main {
	public static void main(String[] args) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		int k,a,b,x;
		Scanner sc = new Scanner(System.in);
		
		k = Integer.parseInt(sc.next());
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		
		sc.close();
		
		x = (b / k) * k;
		if(a <= x) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}