import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	}
} Main public static void main(String[] args) {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	} main {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

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

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	}
} public class Main {
	public static void main(String[] args) {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int k;
		int a, b;
		String message = "NG";
		Scanner scan = new Scanner(System.in);

		k = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				message = "OK";
				break;
			}
		}

		System.out.println(message);
	}
}
