import java.util.*;

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

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

  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int n = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    for(int i=a;i<=b;i++){
      if (i%n == 0){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");

  } main {
    Scanner scan = new Scanner(System.in);
    int n = scan.nextInt();
    int a = scan.nextInt();
    int b = scan.nextInt();
    for(int i=a;i<=b;i++){
      if (i%n == 0){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");

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

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

  }
} Main
import java.util.*;

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

  }
}
