import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  } main {
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int k = scan.nextInt(); k scan.nextInt() scan.nextInt scan int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int flag = 0; flag 0 for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    } int i = a; int i = a; i a i <=b i b i++ i++ i {
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    } {
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    } if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      } i%k==0 i%k i k 0 {
        flag++;
        System.out.println("OK");
        break;
      } flag++ flag System.out.println("OK") System.out.println System.out System System.out "OK" break; if (flag == 0){
      System.out.println("NG");
    } flag == 0 flag 0 {
      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){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int k = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    int flag = 0;
    for (int i = a; i <=b; i++){
      if (i%k==0){
        flag++;
        System.out.println("OK");
        break;
      }
    }
    if (flag == 0){
      System.out.println("NG");
    }
  }
}