#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif

int main() {
    int64_t n, k;
    cin >> n >> k;

    long double ans = 0;

    for (int64_t i = 0; i <= n; i++) {
        ans += (long double)(i) / (n + 1);
    }

    cout << fixed << setprecision(20) << ans << endl;

    return 0;
}