ABC_126 - C - Dice and Coin

#include <bits/stdc++.h>

#define forn(l, r) for(int i = l; i < (r); ++i)
#define forj(l, r) for(int j = l; j < (r); ++j)
#define TAM 1000100
#define SYNC ios::sync_with_stdio(0);
#define $ << ' ' <<
#define F first
#define S second
#define endl '\n'


using namespace std;

using ll = long long int;
using ii = pair<int, int>;
using vii = vector<ii>;
using vi = vector<int>;
using graph = vector<vi>;
const int INF = 0x3f3f3f3f;
const int MAXN = 112345;
const ll mod = 1000000007;


int main() {
    //SYNC
    double n, k, ans = 0, i;
    cin >> n >> k;
    for (int j = 1; j <= n; ++j) {
        i = j;
        ans += 1.0/n * pow(0.5, max(0.0, ceil(log2(k/i))));
        //cout << 1.0/n << ' ' << ceil(log2(k/i)) << ' ' << pow(0.5, ceil(log2(k/i))) << endl;
    }
    cout << fixed << setprecision(12);
    cout << ans << endl;
    return 0;
}