#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <queue>
#include <cmath>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)

int main(void){
	double n; cin >> n;
	double ans = 4 * pow(3.0 / 4.0, n);
	// cout << ans << endl;
	printf("%.10f\n", ans);
	return 0;
}