import java.util.Scanner;

public class Main {
	static int K;
	static int A;
	static int B;
	static int a;
	static int b;
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	static int K;
	static int A;
	static int B;
	static int a;
	static int b;
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	}
} Main static int K; K static int A; A static int B; B static int a; a static int b; b public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	} main {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) K=sc.nextInt() K sc.nextInt() sc.nextInt sc A=sc.nextInt() A sc.nextInt() sc.nextInt sc B=sc.nextInt() B sc.nextInt() sc.nextInt sc a=A/K a A/K A K b=B/K b B/K B K if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		} a!=b a b {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		} a==b&&A%K==0 a==b a b A%K==0 A%K A K 0 {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		} a==b&&B%K==0 a==b a b B%K==0 B%K B K 0 {
			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 {
	static int K;
	static int A;
	static int B;
	static int a;
	static int b;
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	}
} public class Main {
	static int K;
	static int A;
	static int B;
	static int a;
	static int b;
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	}
} Main
import java.util.Scanner;

public class Main {
	static int K;
	static int A;
	static int B;
	static int a;
	static int b;
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
		K=sc.nextInt();
		A=sc.nextInt();
		B=sc.nextInt();
		a=A/K;
		b=B/K;
		if(a!=b) {
			System.out.println("OK");
		}
		else if(a==b&&A%K==0) {
			System.out.println("OK");
		}
		else if(a==b&&B%K==0) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
	}
}
