import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	}
} Main public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	} main {
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	} Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) int K = stdIn.nextInt(); K stdIn.nextInt() stdIn.nextInt stdIn int A = stdIn.nextInt(); A stdIn.nextInt() stdIn.nextInt stdIn int B = stdIn.nextInt(); B stdIn.nextInt() stdIn.nextInt stdIn int ans = 0; ans 0 for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		} int a = A; int a = A; a A a <= B a B a++ a++ a {
			if(a % K == 0){
				ans = 1;
				break;
			}
		} {
			if(a % K == 0){
				ans = 1;
				break;
			}
		} if(a % K == 0){
				ans = 1;
				break;
			} a % K == 0 a % K a K 0 {
				ans = 1;
				break;
			} ans = 1 ans 1 break; if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		} ans == 1 ans 1 {
			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" stdIn.close() stdIn.close stdIn String[] args args public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	}
} public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int K = stdIn.nextInt();
		int A = stdIn.nextInt();
		int B = stdIn.nextInt();
		int ans = 0;

		for(int a = A; a <= B ; a++){
			if(a % K == 0){
				ans = 1;
				break;
			}
		}
		if(ans == 1){
			System.out.println("OK");
		}
		else{
			System.out.println("NG");
		}
		stdIn.close();
	}
}