import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int k = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int k = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    }
} Main public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int k = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    } main {
        Scanner in = new Scanner(System.in);
        int k = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) int k = Integer.parseInt(in.nextLine()); k Integer.parseInt(in.nextLine()) Integer.parseInt Integer in.nextLine() in.nextLine in String[] tmp = in.nextLine().trim().split("\\s"); tmp in.nextLine().trim().split("\\s") in.nextLine().trim().split in.nextLine().trim() in.nextLine().trim in.nextLine() in.nextLine in "\\s" int a = Integer.parseInt(tmp[0]); a Integer.parseInt(tmp[0]) Integer.parseInt Integer tmp[0] tmp 0 int b = Integer.parseInt(tmp[1]); b Integer.parseInt(tmp[1]) Integer.parseInt Integer tmp[1] tmp 1 in.close() in.close in int res = 0; res 0 while(res < a){
            res += k;
        } res < a res a {
            res += k;
        } res += k res k if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        } res <= b res b {
            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 = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            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 = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int k = Integer.parseInt(in.nextLine());
        String[] tmp = in.nextLine().trim().split("\\s");
        int a = Integer.parseInt(tmp[0]);
        int b = Integer.parseInt(tmp[1]);
        in.close();
        int res = 0;
        while(res < a){
            res += k;
        }
        if(res <= b){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
    }
}