
import java.util.*;
import java.io.*;

import static java.lang.Character.isUpperCase;

public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    }



 import java.util.*; util.* java import java.io.*; io.* java import static java.lang.Character.isUpperCase; import static java.lang.Character.isUpperCase; import static java.lang.Character.isUpperCase; public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    } Main public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    } main {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    } Scanner in = new Scanner(System.in); in new Scanner(System.in) int K  =  in.nextInt(); K in.nextInt() in.nextInt in int A  =  in.nextInt(); A in.nextInt() in.nextInt in int B  =  in.nextInt(); B in.nextInt() in.nextInt in boolean x =false; x false for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        } int i = A; int i = A; i A i <= B i B i ++ i ++ i {
            if (i % K == 0) {
                x = true;
            }
        } {
            if (i % K == 0) {
                x = true;
            }
        } if (i % K == 0) {
                x = true;
            } i % K == 0 i % K i K 0 {
                x = true;
            } x = true x true if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            } x == true x true {
                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 in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    } public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    } Main

import java.util.*;
import java.io.*;

import static java.lang.Character.isUpperCase;

public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

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

        boolean x =false;
        for(int i = A; i <= B; i ++) {
            if (i % K == 0) {
                x = true;
            }
        }
            if (x == true) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }

    }




    }




