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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		System.out.println("NG");
	} main {
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		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 for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		} int d = a; int d = a; d a d <= b d b ++d ++d d {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		} {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		} if (d % k == 0) {
				System.out.println("OK");
				return;
			} d % k == 0 d % k d k 0 {
				System.out.println("OK");
				return;
			} System.out.println("OK") System.out.println System.out System System.out "OK" return; 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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		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();
		for (int d = a; d <= b; ++d) {
			if (d % k == 0) {
				System.out.println("OK");
				return;
			}
		}

		System.out.println("NG");
	}

}
