import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	}

	void calc() {
	}

	void showResult() {
	}

} import java.util.*; util.* java import java.io.*; io.* java import java.nio.charset.StandardCharsets; StandardCharsets java.nio.charset public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	}

	void calc() {
	}

	void showResult() {
	}

} Main public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	} main {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	} InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8); reader new InputStreamReader(System.in, StandardCharsets.UTF_8) BufferedReader in = new BufferedReader(reader); in new BufferedReader(reader) Main ins = new Main(in); ins new Main(in) ins.calc() ins.calc ins ins.showResult() ins.showResult ins String[] args args Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	} Main {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	} String[] tokens = in.readLine().split(" "); tokens in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int K = Integer.parseInt(tokens[0]); K Integer.parseInt(tokens[0]) Integer.parseInt Integer tokens[0] tokens 0 tokens = in.readLine().split(" ") tokens in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int A = Integer.parseInt(tokens[0]); A Integer.parseInt(tokens[0]) Integer.parseInt Integer tokens[0] tokens 0 int B = Integer.parseInt(tokens[1]); B Integer.parseInt(tokens[1]) Integer.parseInt Integer tokens[1] tokens 1 boolean enable = false; enable false for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		} int i = A; int i = A; i A i <= B i B ++i ++i i {
			if (i % K == 0) {
				enable = true;
				break;
			}
		} {
			if (i % K == 0) {
				enable = true;
				break;
			}
		} if (i % K == 0) {
				enable = true;
				break;
			} i % K == 0 i % K i K 0 {
				enable = true;
				break;
			} enable = true enable true break; System.out.println((enable ? "OK" : "NG")) System.out.println System.out System System.out (enable ? "OK" : "NG") enable "OK" "NG" BufferedReader in in void calc() {
	} calc {
	} void showResult() {
	} showResult {
	} public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	}

	void calc() {
	}

	void showResult() {
	}

} public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	}

	void calc() {
	}

	void showResult() {
	}

} Main
import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int K = Integer.parseInt(tokens[0]);
		tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		boolean enable = false;
		for (int i = A; i <= B; ++i) {
			if (i % K == 0) {
				enable = true;
				break;
			}
		}
		System.out.println((enable ? "OK" : "NG"));

	}

	void calc() {
	}

	void showResult() {
	}

}