import java.util.Scanner;

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

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

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

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	} main {
		Scanner s = new Scanner(System.in);

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	} Scanner s = new Scanner(System.in); s new Scanner(System.in) int k = s.nextInt(); k s.nextInt() s.nextInt s int a = s.nextInt(); a s.nextInt() s.nextInt s int b = s.nextInt(); b s.nextInt() s.nextInt s int flag = 0; flag 0 for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		} int i = 1; int i = 1; i 1 k * i <= 1000 k * i k i 1000 i++ i++ i {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		} {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		} if(k * i >= a && k * i <= b) {
				flag++;
			} k * i >= a && k * i <= b k * i >= a k * i k i a k * i <= b k * i k i b {
				flag++;
			} flag++ flag if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} flag != 0 flag 0 {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" {
			System.out.println("NG");
		} System.out.println("NG") System.out.println System.out System System.out "NG" s.close() s.close s String[] args args public class Main {
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	}
} public class Main {
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	}
} Main
import java.util.Scanner;

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

		int k = s.nextInt();
		int a = s.nextInt();
		int b = s.nextInt();
		int flag = 0;

		for (int i = 1; k * i <= 1000; i++) {
			if(k * i >= a && k * i <= b) {
				flag++;
			}
		}

		if(flag != 0) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		s.close();

	}
}
