#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;

int main(){
    int n;
    cin >> n;
    vector<double> C = {6,15,20,15,6};
    vector<double> res(5,1.0);
    rep(i,n)rep(j,5){
        res[j] *= (j+1)/6.0;
    }

    double ans = 0;
    for(int i=1;i<=6;i++){
        if(i%2==0) ans -= C[i-1] * res[i-1];
        else  ans += C[i-1] * res[i-1];
    }
    cout << setprecision(20) << 1 - ans << endl;
    return 0;
}