#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>
#define repd(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
#define mod 1000000007
#define inf 2000000007
#define mp make_pair
#define pb push_back
typedef long long ll;
using namespace std;
template <typename T>
inline void output(T a, int p = 0) {
    if(p) cout << fixed << setprecision(p)  << a << "\n";
    else cout << a << "\n";
}
// end of template
int p, q;
double f(int cur = p, int depth = 0){
    if(depth >= 20) return 1.0;
    double win = double(p) / 200.0 + double(100 - p) / 300.0;
    double draw_y = double(p) * f(max(0, p - q), depth + 1) / 200.0;
    double draw_n = double(100 - p) * f(min(100, p + q), depth + 1) / 300.0;
    return win + draw_y + draw_n;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    // source code
    
    cin >> p >> q;
    
    double ret = 1.0 / 3.0 + 1.0 / 3.0 * f();
    
    output(ret, 10);
    
    return 0;
}