import java.util.Scanner;

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

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	}
} Main public static void main(String[] args) {

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	} main {

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	} Scanner scnr = new Scanner(System.in); scnr new Scanner(System.in) int k = scnr.nextInt(); k scnr.nextInt() scnr.nextInt scnr int a = scnr.nextInt(); a scnr.nextInt() scnr.nextInt scnr int b = scnr.nextInt(); b scnr.nextInt() scnr.nextInt scnr int counter = 0; counter 0 for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if(i % k == 0) {
				counter = counter + 1;
			}
		} {
			if(i % k == 0) {
				counter = counter + 1;
			}
		} if(i % k == 0) {
				counter = counter + 1;
			} i % k == 0 i % k i k 0 {
				counter = counter + 1;
			} counter = counter + 1 counter counter + 1 counter 1 if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		} counter == 0 counter 0 {
			System.out.print("NG");
		} System.out.print("NG") System.out.print System.out System System.out "NG" if (counter > 0) {
			System.out.print("OK");
		} counter > 0 counter 0 {
			System.out.print("OK");
		} System.out.print("OK") System.out.print System.out System System.out "OK" String[] args args public class Main {
	public static void main(String[] args) {

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	}
} public class Main {
	public static void main(String[] args) {

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	}
} Main
import java.util.Scanner;

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

		Scanner scnr = new Scanner(System.in);
		int k = scnr.nextInt();
		int a = scnr.nextInt();
		int b = scnr.nextInt();

		int counter = 0;

		for (int i = a; i <= b; i++) {
			if(i % k == 0) {
				counter = counter + 1;
			}
		}

		if (counter == 0) {
			System.out.print("NG");
		}
		else if (counter > 0) {
			System.out.print("OK");
		}
	}
}