import java.util.Scanner;
public 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 
} import java.util.Scanner; Scanner java.util public 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 
} 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } main {
        Scanner sc= new Scanner(System.in);
        int K = sc.nextInt();
      int A = sc.nextInt();
      int B = sc.nextInt();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 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 String ans = "NG"; ans "NG" int ak = A / K; ak A / K A K for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      } int i = ak; int i = ak; i ak i * K <= B i * K i K B i++ i++ i {
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      } {
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      } int ik = i * K; ik i * K i K if(A <= ik && ik <= B){
          ans = "OK";
          break;
        } A <= ik && ik <= B A <= ik A ik ik <= B ik B {
          ans = "OK";
          break;
        } ans = "OK" ans "OK" break; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 
} public 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 
} Main
import java.util.Scanner;
public 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();
      String ans = "NG";
      int ak = A / K;
      for(int i = ak; i * K <= B; i++){
        int ik = i * K;
        if(A <= ik && ik <= B){
          ans = "OK";
          break;
        }
      }
      System.out.println(ans);
    } 
}