import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int multiple = Integer.parseInt(br.readLine()); multiple Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String input = br.readLine(); input br.readLine() br.readLine br String[] inputArray = input.split(" "); inputArray input.split(" ") input.split input " " int start = Integer.parseInt(inputArray[0]); start Integer.parseInt(inputArray[0]) Integer.parseInt Integer inputArray[0] inputArray 0 int end = Integer.parseInt(inputArray[1]); end Integer.parseInt(inputArray[1]) Integer.parseInt Integer inputArray[1] inputArray 1 for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} int i = start; int i = start; i start i <= end i end i++ i++ i {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			} i % multiple == 0 i % multiple i multiple 0 {
				System.out.println("OK");
				System.exit(0);
			} System.out.println("OK") System.out.println System.out System System.out "OK" System.exit(0) System.exit System 0 System.out.println("NG") System.out.println System.out System System.out "NG" System.exit(0) System.exit System 0 String[] args args public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	}
} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int multiple = Integer.parseInt(br.readLine());
		String input = br.readLine();
		String[] inputArray = input.split(" ");
		
		int start = Integer.parseInt(inputArray[0]);
		int end = Integer.parseInt(inputArray[1]);
		
		for (int i = start; i <= end; i++) {
			if (i % multiple == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
		System.exit(0);
	}
}