#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T, class U> using Pa = pair<T, U>;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N,K;
    cin >> N >> K;
    double ans = 0;
    for(int i=1;i<=N;i++){
        ans += 1.0*i/(N+1);
    }
    cout << fixed << setprecision(10) << ans << "\n";
}