#include <bits/stdc++.h>
using namespace std;

#define mp make_pair
using ll = long long; using ld = long double; 
using P = pair<ld, ld>;
#define ldout fixed << setprecision(40) 

static const double EPS = 1e-14;
static const long long INF = 1e18;
static const long long mo = 1e9+7;

ld p0, q; 
ll search_depth;
map<pair<ld, ll>, ld> memo;
ld dfs(ld p, ll depth) {
    if (memo.count(mp(p, depth))) 
        return memo[mp(p, depth)];
    if (depth > search_depth) return 1;
    return memo[mp(p, depth)] = p / 2 + (1 - p) / 3 + dfs(max(0.0l, p - q), depth + 1) * p / 2 + dfs(min(1.0l, p + q), depth + 1) * (1 - p) / 3;
}

int main(void) {
    cin >> p0 >> q;

    search_depth = 112;
    cout << ldout << (1.0l + dfs(p0, 0)) / 3 << endl;
    return 0;
}