#include <bits/stdc++.h> #define rep(i, a, n) for(int i = a; i < n; i++) #define REP(i, n) rep(i, 0, n) #define repb(i, a, b) for(int i = a; i >= b; i--) #define all(a) a.begin(), a.end() #define int long long #define chmax(x, y) x = max(x, y) #define chmin(x, y) x = min(x, y) using namespace std; typedef pair<int, int> P; const int mod = 1000000007; const int INF = 1e12; double c[51][51]; void f(){ rep(i, 0, 51) c[i][0] = 1; rep(i, 1, 51){ rep(j, 1, 51){ c[i][j] = c[i - 1][j - 1] + c[i - 1][j]; } } } signed main(){ // ios::sync_with_stdio(false); // cin.tie(0); int n; cin >> n; f(); double ans = 0.0; if(n >= 6){ int k = -1; rep(i, 1, 7){ ans += (double)k * c[6][i] * pow((double)i / (double)6, n); k *= -1; } } printf("%.15lf\n", ans); }