code:

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

int main()
{
    int a;
    double ans;
    cin >> a;
    for (int i = 1; i <= a; i++)
    {
        ans += pow(-1, i - 1) * (1 / i);
    }
    cout << fixed << setprecision(4) << ans;
    return 0;
}