#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int main() {
    int N; cin >> N;
    double ans = 0.;
    rep(i, 1000000 / N) ans += pow(double(i + 1), -N);
    cout << fixed << setprecision(10) << ans << endl;

    return 0;
}