import java.util.Scanner;
 
public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  }
} import java.util.Scanner; Scanner java.util public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  } main {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int k = sc.nextInt() k sc.nextInt() sc.nextInt sc a = sc.nextInt() a sc.nextInt() sc.nextInt sc b = sc.nextInt(); b sc.nextInt() sc.nextInt sc if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    } a % k == 0 || b % k == 0 a % k == 0 a % k a k 0 b % k == 0 b % k b k 0 {
      System.out.println("OK");
    } System.out.println("OK") System.out.println System.out System System.out "OK" {
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    } if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      } b/k - a/k == 0 b/k - a/k b/k b k a/k a k 0 {
        System.out.println("NG");
      } System.out.println("NG") System.out.println System.out System System.out "NG" {
        System.out.println("OK");
      } System.out.println("OK") System.out.println System.out System System.out "OK" String[] args args public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  }
} public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  }
} Main
import java.util.Scanner;
 
public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    final int k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
    if(a % k == 0 || b % k == 0){
      System.out.println("OK");
    }else{
      if(b/k - a/k == 0){
        System.out.println("NG");
      }else{
        System.out.println("OK");
      }
    }
  }
}