import java.lang.reflect.Array;
import java.util.*;
import java.io.*;
import java.lang.*;

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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    }
} import java.lang.reflect.Array; Array java.lang.reflect import java.util.*; util.* java import java.io.*; io.* java import java.lang.*; lang.* java 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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    }
} 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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

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

        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    } 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 String ans = "NG"; ans "NG" for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        } int i = a; int i = a; i a i<b+1 i b+1 b 1 i++ i++ i {
            if (i%k == 0){
                ans = "OK";
                break;
            }
        } {
            if (i%k == 0){
                ans = "OK";
                break;
            }
        } if (i%k == 0){
                ans = "OK";
                break;
            } i%k == 0 i%k i k 0 {
                ans = "OK";
                break;
            } ans = "OK" ans "OK" break; System.out.println(ans) System.out.println System.out System System.out ans 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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    }
} 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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    }
} Main
import java.lang.reflect.Array;
import java.util.*;
import java.io.*;
import java.lang.*;

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();

        String ans = "NG";
        for (int i = a;i<b+1;i++){
            if (i%k == 0){
                ans = "OK";
                break;
            }
        }
        System.out.println(ans);

    }
}
