#include <iostream>
#include <vector>
#include<iomanip>
#include<functional>
#include<algorithm>
#include<deque>
#include<math.h>
#include<set>
#include<string>
#include<queue>
#include<map>
using namespace std;
#define rep(i,n) for(ll i = 0;i<n;i++)
#define req(i,n) for(ll i = 1;i<=n;i++)
#define rrep(i,n) for(int i = n-1;i>=0;i--)
#define ALL(a) a.begin(),a.end()
template<class T> inline bool chmax(T & a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T & a, T b) { if (a > b) { a = b; return 1; } return 0; }
typedef long long ll;
typedef long double d;
const ll INF = 1<<61;
int main() {
    int n; cin >> n;
    d a[110]; a[0] = 4; a[1] = 3;
    req(i, 100) a[i + 1] = a[i]*0.75;
    cout << fixed << setprecision(10) << a[n] << endl;
}