import java.util.Scanner;
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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	}
} 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();
		int A = sc.nextInt();
		int B = sc.nextInt();

		if (A % K == 0) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	}
} 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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	} main {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		if (A % K == 0) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	} 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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		} A % K == 0 A % K A K 0 {
			System.out.print("OK");
		} System.out.print("OK") System.out.print System.out System System.out "OK" if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		} B % K == 0 B % K B K 0 {
			System.out.print("OK");
		} System.out.print("OK") System.out.print System.out System System.out "OK" if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		} (A / K + 1) * K < B (A / K + 1) * K (A / K + 1) A / K A K 1 K B {
			System.out.print("OK");
		} System.out.print("OK") System.out.print System.out System System.out "OK" {
			System.out.print("NG");
		} System.out.print("NG") System.out.print System.out System System.out "NG" return; 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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	}
} 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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	}
} Main
import java.util.Scanner;
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) {
			System.out.print("OK");
		} else if (B % K == 0) {
			System.out.print("OK");
		} else if ((A / K + 1) * K < B) {
			System.out.print("OK");
		} else {
			System.out.print("NG");
		}
		
	return;

	}
}
