import 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 <= (b/k)*k) System.out.println("OK");
      	else System.out.println("NG");
    }
} import java.util.*; util.* 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();
      	if(a <= (b/k)*k) 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();
      	if(a <= (b/k)*k) 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();
      	if(a <= (b/k)*k) 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 if(a <= (b/k)*k) System.out.println("OK");
      	else System.out.println("NG"); a <= (b/k)*k a (b/k)*k (b/k) b k k System.out.println("OK") System.out.println System.out System System.out "OK" 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 sc = new Scanner(System.in);
      	int k = sc.nextInt();
      	int a = sc.nextInt();
      	int b = sc.nextInt();
      	if(a <= (b/k)*k) System.out.println("OK");
      	else System.out.println("NG");
    }
} 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 <= (b/k)*k) System.out.println("OK");
      	else System.out.println("NG");
    }
} Main
import 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 <= (b/k)*k) System.out.println("OK");
      	else System.out.println("NG");
    }
}