import java.util.Scanner;

public class Main {

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	}

} import java.util.Scanner; Scanner java.util public class Main {

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	}

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	} main {
		Scanner scanner = new Scanner(System.in);

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) Integer K = Integer.parseInt(scanner.next()); K Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner Integer A = Integer.parseInt(scanner.next()); A Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner Integer B = Integer.parseInt(scanner.next()); B Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner int a = A / K; a A / K A K int num = A % K; num A % K A K if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		} num == 0 num 0 {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			} a * K <= B a * K a K B {
				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" {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		} if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			} (a+1) * K <= B (a+1) * K (a+1) a 1 K B {
				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" String[] args args public class Main {

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	}

} public class Main {

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	}

} Main
import java.util.Scanner;

public class Main {

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

		Integer K = Integer.parseInt(scanner.next());
		Integer A = Integer.parseInt(scanner.next());
		Integer B = Integer.parseInt(scanner.next());

		int a = A / K;
		int num = A % K;
		if (num == 0) {
			if (a * K <= B) {
				System.out.println("OK");
			} else {
				System.out.println("NG");
			}
		} else {
			if ((a+1) * K <= B) {
				System.out.println("OK");;
			} else {
				System.out.println("NG");
			}
		}
	}

}
