import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    double ans = 4;
    if(n > 0) {
      for(int i = 0; i < n; i++) {
        ans *= (double)0.75;
      }
    }
    System.out.println(ans);
  }
}