
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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	}
} 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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	}
} 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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	} main {

		Scanner scan = new Scanner(System.in);
		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	} 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 if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		} A % K == 0 A % K A K 0 {

			System.out.println("OK");

		} System.out.println("OK") System.out.println System.out System System.out "OK" if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		} (K - A % K) + A <= B (K - A % K) + A (K - A % K) K A % K A K A B {

			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" scan.close() scan.close scan 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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	}
} 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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	}
} 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();

		if (A % K == 0) {

			System.out.println("OK");

		} else if ((K - A % K) + A <= B) {

			System.out.println("OK");

		} else {

			System.out.println("NG");

		}

		scan.close();
	}
}
