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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	}
} 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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	}
} 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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	} main {

		Scanner sc = new Scanner(System.in);

		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	} 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 String ans = "NG"; ans "NG" for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		} int i = 1; int i = 1; i 1 i <= 1000 i 1000 i++ i++ i {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		} {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		} int n = K * i; n K * i K i if (A <= n && n <= B) {
				ans = "OK";
				break;
			} A <= n && n <= B A <= n A n n <= B n B {
				ans = "OK";
				break;
			} ans = "OK" ans "OK" break; System.out.println(ans) System.out.println System.out System System.out ans 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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	}
} 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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	}
} 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();

		String ans = "NG";

		for (int i = 1; i <= 1000; i++) {

			int n = K * i;

			if (A <= n && n <= B) {
				ans = "OK";
				break;
			}
		}

		// 出力
		System.out.println(ans);
	}
}