githubNonFunziona/2-3-g.spp

#include <iostream>
int main() {
    int a;
    std::cin >> a;
    double b = 1;
    double c = 0.0;
    for (int i = 1; i <= a; ++i) {
        c += b / i;
        b = -b;
    }
    std::cout << c << "\n";
}