import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				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 multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		}
	} main {
		Scanner sc = new Scanner(System.in);

		int multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int multi_num = sc.nextInt(); multi_num sc.nextInt() sc.nextInt sc int low_lim = sc.nextInt(); low_lim sc.nextInt() sc.nextInt sc int high_lim = sc.nextInt(); high_lim sc.nextInt() sc.nextInt sc for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		} int i = low_lim; int i = low_lim; i low_lim i <= high_lim i high_lim i++ i++ i {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		} {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		} if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			} i % multi_num ==0 i % multi_num i multi_num 0 {
				System.out.println("OK");
				break;
			} System.out.println("OK") System.out.println System.out System System.out "OK" break; if (i == high_lim) {
				System.out.println("NG");
			} i == high_lim i high_lim {
				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 multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		}
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				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 multi_num = sc.nextInt();
		int low_lim = sc.nextInt();
		int high_lim = sc.nextInt();

		for (int i = low_lim; i <= high_lim; i++) {
			if (i % multi_num ==0) {
				System.out.println("OK");
				break;
			}
			if (i == high_lim) {
				System.out.println("NG");
			}
		}
	}
}