import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			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 sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	}

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

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	} main {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = sc.nextInt(); K sc.nextInt() sc.nextInt sc int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int count = 0; count 0 for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if (i % K == 0) {
				count++;
			}
		} {
			if (i % K == 0) {
				count++;
			}
		} if (i % K == 0) {
				count++;
			} i % K == 0 i % K i K 0 {
				count++;
			} count++ count if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} count > 0 count 0 {
			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 sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	}

} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int count = 0;

		for (int i = a; i <= b; i++) {
			if (i % K == 0) {
				count++;
			}
		}

		if (count > 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

	}

}