#include <iostream>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <cstdio>
#include <sstream>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <set>
#include <map>
#include <list>
#include <iomanip>

#define INF 1000000001
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (a); i >= (b); i--)

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
const double PI = acos(-1.0);


int main()
{
	ios::sync_with_stdio(false);

	int n;
	cin >> n;
	double ans = 4.0*pow(3.0/4.0,n);
	cout << setprecision(15) << ans << endl;
}