import java.util.*;
 
public class Main { //クラス名はMain
    public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    }
} import java.util.*; util.* java public class Main { //クラス名はMain
    public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    }
} Main public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    } main {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = Integer.parseInt(sc.next()); K Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int A = Integer.parseInt(sc.next()); A Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int B = Integer.parseInt(sc.next()); B Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc String answer = "NG"; answer "NG" for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      } int i=1; int i=1; i 1 K*i<=1000 K*i K i 1000 i++ i++ i {
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      } {
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      } if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        } A <= K*i && B >= K * i A <= K*i A K*i K i B >= K * i B K * i K i {
          answer = "OK";
          break;
        } answer = "OK" answer "OK" break; {
          answer = "NG";
        } answer = "NG" answer "NG" System.out.println(answer) System.out.println System.out System System.out answer String[] args args public class Main { //クラス名はMain
    public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    }
} public class Main { //クラス名はMain
    public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    }
} Main
import java.util.*;
 
public class Main { //クラス名はMain
    public static void main(String[] args) {
      //整数の入力
      // List<String> list = new ArrayList<String>();
      Scanner sc = new Scanner(System.in);
      int K = Integer.parseInt(sc.next());
      int A = Integer.parseInt(sc.next());
      int B = Integer.parseInt(sc.next());

      //黒板の整数
      String answer = "NG"; 
      for(int i=1; K*i<=1000; i++){
        if(A <= K*i && B >= K * i){
          answer = "OK";
          break;
        }else {
          answer = "NG";
        }
      }
      System.out.println(answer);
    }
}