#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b)*b; }
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }

/*
 <url:>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */


double dp[1005][101];
template<class T>
T solve(T res){
    int p,q; cin >> p >> q;
    dp[0][p] = res = 1/3.0;
    for(int i = 0; i <= 1000;i++){
        for(int j = 0; j < 101;j++){
            if(abs(dp[i][j]) < 1e-9) continue;
            res += dp[i][j]*(j/100.0)/2.0;
            dp[i+1][max(j-q,0)] += dp[i][j]*(j/100.0)/2.0;
            
            res += dp[i][j]*(1-j/100.0)/3.0;
            dp[i+1][min(j+q,100)] += dp[i][j]*(1-j/100.0)/3.0;
        }
    }
    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(15) << solve(0.0) << endl;
    return 0;
}