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

#define _p(...) (void)printf(__VA_ARGS__)
#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define ALL(x) (x).begin(), (x).end()
#define BIT(n) (1LL<<(n))
#define SZ(x) ((int)(x).size())
#define fst first
#define snd second
using ll=long long;using pii=pair<int,int>;using vb=vector<bool>;
using vi=vector<int>;using vvi=vector<vi>;using vvvi=vector<vvi>;
using vl=vector<ll>;using vvl=vector<vl>;using vvvl=vector<vvl>;
using vd=vector<double>;using vvd=vector<vd>;using vvvd=vector<vvd>;
using vpii=vector<pii>;using vvpii=vector<vpii>;using vvvpii=vector<vvpii>;

void Main() {
  int p0, q;
  cin >> p0 >> q;

  const int T = 20000000;

  queue<pair<int, double>> que;

  que.emplace(p0, 1./3);
  double w = 1./3, l = 1./3;

  rep(_, T) {
    int p; double d;
    tie(p, d) = que.front(); que.pop();
    double p2 = p/100./2;
    double p3 = (100-p)/100./3;
    w += d * p2 + d * p3;
    l += d * p3;
    double d1 = d * p2;
    double d2 = d * p3;
    que.emplace(max(0, p - q), d1);
    que.emplace(min(100, p + q), d2);
  }
  //cout<<"w: "<<w<<endl;
  //cout<<"l: "<<l<<endl;
  _p("%.10f\n", w / (w+l));
}
int main() { cin.tie(0); ios::sync_with_stdio(false); Main(); return 0; }