import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            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 sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int k = sc.nextInt(); k sc.nextInt() sc.nextInt sc int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        } a / k == b / k && a % k != 0 && b % k != 0 a / k == b / k && a % k != 0 && b % k != 0 a / k == b / k a / k a k b / k b k a % k != 0 a % k a k 0 b % k != 0 b % k b k 0 {
            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 sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if(a / k == b / k && a % k != 0 && b % k != 0){
            System.out.println("NG");
        } else {
            System.out.println("OK");
        }
    }
}