import 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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "OK" : "NG");	
		}
	}
} import java.util.*; util.* java 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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "OK" : "NG");	
		}
	} main {
	
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "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 if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "OK" : "NG");	
		} a % k  == 0 || b % k == 0 a % k  == 0 a % k a k 0 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(b / k - a / k >=1 ? "OK" : "NG");	
		} System.out.println(b / k - a / k >=1 ? "OK" : "NG") System.out.println System.out System System.out b / k - a / k >=1 ? "OK" : "NG" b / k - a / k >=1 b / k - a / k b / k b k a / k a k 1 "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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "OK" : "NG");	
		}
	}
} Main
import 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();
		if(a % k  == 0 || b % k == 0) {
			System.out.println("OK");
		} else {
			System.out.println(b / k - a / k >=1 ? "OK" : "NG");	
		}
	}
}