#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
ll mod=1e9+7;

int main() {
    ll N;
    cin>>N;
    vector<vector<double>> DP(N+1,vector<double>(7,0));
    DP[0][0]=1.0;
    rep(i,N){
        rep(j,7){
            if(j==6)DP[i+1][j]+=DP[i][j];
            else{
                DP[i+1][j]+=double(j)/6.0*DP[i][j];
                DP[i+1][j+1]+=double(6.0-j)/6.0*DP[i][j];
            }
        }
    }
    cout<<setprecision(16)<<DP[N][6]<<endl;

}