import java.util.*;
 
public class Main{
  public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  }
} Main public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  } main {
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  } Scanner sc =  new Scanner(System.in); sc new Scanner(System.in) int N = Integer.parseInt(sc.nextLine()); N Integer.parseInt(sc.nextLine()) Integer.parseInt Integer sc.nextLine() sc.nextLine 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" for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    } int i = A; int i = A; i A i <= B i B i++ i++ i {
      if(i%N==0){
        ans = "OK";
        break;
      }
    } {
      if(i%N==0){
        ans = "OK";
        break;
      }
    } if(i%N==0){
        ans = "OK";
        break;
      } i%N==0 i%N i N 0 {
        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 N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  }
} public class Main{
  public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  }
} Main
import java.util.*;
 
public class Main{
  public static void main(String[]args){
    Scanner sc =  new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i <= B; i++){
      if(i%N==0){
        ans = "OK";
        break;
      }
    }
    System.out.println(ans);
  }
}