import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	}

} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	} main {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int K = scan.nextInt(); K scan.nextInt() scan.nextInt scan int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan int f = 0; f 0 for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		} int i = A; int i = A; i A i <= B i B i++ i++ i {
			if (i % K ==0) {
				f++;
				break;
			}
		} {
			if (i % K ==0) {
				f++;
				break;
			}
		} if (i % K ==0) {
				f++;
				break;
			} i % K ==0 i % K i K 0 {
				f++;
				break;
			} f++ f break; if (f == 0) System.out.println("NG"); f == 0 f 0 System.out.println("NG") System.out.println System.out System System.out "NG" if (f == 1) System.out.println("OK"); f == 1 f 1 System.out.println("OK") System.out.println System.out System System.out "OK" String[] args args public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	}

} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int f = 0;

		for (int i = A; i <= B; i++) {
			if (i % K ==0) {
				f++;
				break;
			}
		}

		if (f == 0) System.out.println("NG");
		if (f == 1) System.out.println("OK");

	}

}