import java.util.*;
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();
        boolean ans=false;
        for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        }
        if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
   
    }
} import java.util.*; util.* java 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();
        boolean ans=false;
        for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        }
        if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
   
    }
} 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();
        boolean ans=false;
        for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        }
        if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
   
    } main {
        Scanner sc= new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        boolean ans=false;
        for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        }
        if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
   
    } 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 boolean ans=false; ans false for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        } int d=a; int d=a; d a d<=b d b d++ d++ d {
            if(d%k==0){
                ans=true;
                break;
            }
        } {
            if(d%k==0){
                ans=true;
                break;
            }
        } if(d%k==0){
                ans=true;
                break;
            } d%k==0 d%k d k 0 {
                ans=true;
                break;
            } ans=true ans true break; if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        } ans {
            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
import java.util.*;
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();
        boolean ans=false;
        for (int d=a;d<=b;d++){
            if(d%k==0){
                ans=true;
                break;
            }
        }
        if(ans){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
   
    }
}