#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using ll = long long;

int n;

void solve(){
	printf("%.20lf\n",4.0*pow(3.0/4.0,n));
}

signed main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cin >> n;
	solve();
}