#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <cstdlib>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional> 
#include <iomanip>
#include <unordered_map>
#include <memory.h>
#include <unordered_set>
#include <fstream>
#include <random>

using namespace std;

long double mypow(long double r, int n)
{
	long double res = 1;
	while (n > 0)
	{
		if (n % 2 == 1)
		{
			res *= r;
		}
		r *= r;
		n /= 2;
	}
	return res;
}

int main(void)
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	//A_N = 4*(3/4)^N

	int N;

	cin >> N;

	long double res = 4;
	res *= mypow(0.75, N);

	cout << fixed;
	cout.precision(9);

	cout << res << '\n';


	return 0;
}