#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

typedef long long ll;
typedef pair<int, int> P;

const ll mod =  1000000007;  //出力は (ans % mod + mod) % mod  (負の剰余を正にする)
const int inf = 1e9;
const long long INF = 1LL << 60;   // INF = 1152921504606846976

int main()
{
    int n,m;
    cin >> n >> m;
    double ans = 0;
    rep(i,n+1) ans += (double)i/(n+1);
    printf("%.10lf",ans);
}