import java.io.*;
import 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        }
} import java.io.*; io.* java import java.util.*; util.* java 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        }
} 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        } main {
                Scanner scan = new Scanner(System.in);

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

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        } 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 int syou = A/K; syou A/K A K int hantei = K * syou; hantei K * syou K syou while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                } true {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                } if (hantei > B) {
                                System.out.println("NG");
                                break;
                        } hantei > B hantei B {
                                System.out.println("NG");
                                break;
                        } System.out.println("NG") System.out.println System.out System System.out "NG" break; if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        } hantei >= A hantei A {
                                System.out.println("OK");
                                break;
                        } System.out.println("OK") System.out.println System.out System System.out "OK" break; hantei += K hantei K 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        }
} 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        }
} Main
import java.io.*;
import 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();

                int syou = A/K;
                int hantei = K * syou;

                while (true) {
                        if (hantei > B) {
                                System.out.println("NG");
                                break;
                        }
                        if (hantei >= A) {
                                System.out.println("OK");
                                break;
                        }
                        hantei += K;
                }
        }
}