import java.util.Scanner;
//import java.util.Arrays;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	}
} 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(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	} main {
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int 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 String s = "NG"; s "NG" for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if(i % k == 0){
				s = "OK";
				break;
			}
		} {
			if(i % k == 0){
				s = "OK";
				break;
			}
		} if(i % k == 0){
				s = "OK";
				break;
			} i % k == 0 i % k i k 0 {
				s = "OK";
				break;
			} s = "OK" s "OK" break; System.out.println(s) System.out.println System.out System System.out s String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	}
} Main
import java.util.Scanner;
//import java.util.Arrays;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		String s = "NG";
		for(int i = a; i <= b; i++){
			if(i % k == 0){
				s = "OK";
				break;
			}
		}
		System.out.println(s);
	}
}
