import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    }
} Main public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    } main {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    } Scanner scn = new Scanner(System.in); scn new Scanner(System.in) int k=scn.nextInt(); k scn.nextInt() scn.nextInt scn int a=scn.nextInt(); a scn.nextInt() scn.nextInt scn int b=scn.nextInt(); b scn.nextInt() scn.nextInt scn for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      } ; a<=b a b a++ a++ a {
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      } {
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      } if(a%k==0){
            System.out.printf("OK\n");
            return;
          } a%k==0 a%k a k 0 {
            System.out.printf("OK\n");
            return;
          } System.out.printf("OK\n") System.out.printf System.out System System.out "OK\n" return; System.out.printf("NG\n") System.out.printf System.out System System.out "NG\n" String[] args args public class Main {
    public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    }
} public class Main {
    public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
      Scanner scn = new Scanner(System.in);
      int k=scn.nextInt();
      int a=scn.nextInt();
      int b=scn.nextInt();
      for(;a<=b;a++){
          if(a%k==0){
            System.out.printf("OK\n");
            return;
          }
      }
      System.out.printf("NG\n");
    }
}
