import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	}

} import java.util.Scanner; Scanner java.util public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	}

} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	} main {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	} Scanner scn= new Scanner(System.in); scn new Scanner(System.in) int k = scn.nextInt(); k scn.nextInt() scn.nextInt scn int a=scn.nextInt(); a scn.nextInt() scn.nextInt scn int b=scn.nextInt(); b scn.nextInt() scn.nextInt scn if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          } a%k==0 || b%k==0 || (b/k-a/k)>0 a%k==0 || b%k==0 || (b/k-a/k)>0 a%k==0 a%k a k 0 b%k==0 b%k b k 0 (b/k-a/k)>0 (b/k-a/k) b/k b k a/k a k 0 {
        	  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) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	}

} public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	}

} Main
import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
          Scanner scn= new Scanner(System.in);
          int k = scn.nextInt();
          int a=scn.nextInt();
          int b=scn.nextInt();
          if(a%k==0 || b%k==0 || (b/k-a/k)>0){
        	  System.out.println("OK");
        	 
          }else{
        	  System.out.println("NG");
          }
         
	}

}