import java.util.Scanner;

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();

    int x = b/k*k;
    System.out.println(x>=a?"OK":"NG");
  }
} import java.util.Scanner; Scanner 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();

    int x = b/k*k;
    System.out.println(x>=a?"OK":"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();

    int x = b/k*k;
    System.out.println(x>=a?"OK":"NG");
  } main {
    Scanner sc = new Scanner(System.in);
    int k =  sc.nextInt();
    int a =  sc.nextInt();
    int b =  sc.nextInt();

    int x = b/k*k;
    System.out.println(x>=a?"OK":"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 int x = b/k*k; x b/k*k b/k b k k System.out.println(x>=a?"OK":"NG") System.out.println System.out System System.out x>=a?"OK":"NG" x>=a x a "OK" "NG" String[] args args
import java.util.Scanner;

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();

    int x = b/k*k;
    System.out.println(x>=a?"OK":"NG");
  }
}