import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.*;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io import java.util.*; util.* java public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  }
} Main public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  } main {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  } BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) int k = Integer.parseInt(in.readLine()); k Integer.parseInt(in.readLine()) Integer.parseInt Integer in.readLine() in.readLine in String str[] = in.readLine().split(" "); str in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int a = Integer.parseInt(str[0]); a Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int b = Integer.parseInt(str[1]); b Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 in.close() in.close in int largest = (b/k) * k; largest (b/k) * k (b/k) b k k System.out.println(a<=largest?"OK":"NG") System.out.println System.out System System.out a<=largest?"OK":"NG" a<=largest a largest "OK" "NG" String[] args args public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  }
} public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.*;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int k = Integer.parseInt(in.readLine());
    String str[] = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    in.close();
    int largest = (b/k) * k;
    System.out.println(a<=largest?"OK":"NG");
  }
}