#include <bits/stdc++.h>
using namespace std;

int main(int argc, char const *argv[])
{
    int n;
    cin >> n;
    double ans = 0;
    for (int i = 1; i < 1000000; i++)
    {
        ans += pow(i, -(n + 2));
    }
    cout << setprecision(17) << ans << endl;
    return 0;
}