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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "NG");
  } main {
    Scanner scan = new Scanner(System.in);
    int K = scan.nextInt();
    int A = scan.nextInt();
    int B = scan.nextInt();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "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 scan.close() scan.close scan System.out.println(A%K == 0 || A/K != B/K ? "OK" : "NG") System.out.println System.out System System.out A%K == 0 || A/K != B/K ? "OK" : "NG" A%K == 0 || A/K != B/K A%K == 0 A%K A K 0 A/K != B/K A/K A K B/K B K "OK" "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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "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();
    scan.close();

    System.out.println(A%K == 0 || A/K != B/K ? "OK" : "NG");
  }
}