import java.util.Scanner;

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int K = scan.nextInt(); K scan.nextInt() scan.nextInt scan int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		} A / K == B / K A / K A K B / K B K {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		} if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			} A % K == 0 A % K A K 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" {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

	}
} Main
import java.util.Scanner;

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

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

		if(A / K == B / K) {
			if(A % K == 0) {
				System.out.println("OK");
			}else {
				System.out.println("NG");
			}
		}else {
			System.out.println("OK");
		}

	}
}