import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	} main {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) long K = scanner.nextLong(); K scanner.nextLong() scanner.nextLong scanner long a = scanner.nextLong(); a scanner.nextLong() scanner.nextLong scanner long b = scanner.nextLong(); b scanner.nextLong() scanner.nextLong scanner long a1; a1 long b1; b1 a1 = a/K a1 a/K a K b1 = b/K b1 b/K b K if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} K == 1 K 1 {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} a % K == 0 || b % K == 0 a % K == 0 a % K a K 0 b % K == 0 b % K b K 0 {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} b1 != a1 b1 a1 {
			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" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		long K = scanner.nextLong();
		long a = scanner.nextLong();
		long b = scanner.nextLong();
		long a1;
		long b1;
		a1 = a/K;
		b1 = b/K;
		if (K == 1) {
			System.out.println("OK");
		} else if(a % K == 0 || b % K == 0) {
			System.out.println("OK");
		} else if (b1 != a1) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
}
