#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

int p0, q;

const int LIM = 200000;
ld dp[101][LIM+1];

ld f(int p, int r) {
    ld &res = dp[p][r];
    if (res >= -1) return res;

    res = 0;
    if(r < LIM){
        ld p_ = p / 100.0;
        res += p_     * (1.0/2) * f(max(0,   p-q), r+1); // d
        res += p_     * (1.0/2) * 1; // w
        res += (1-p_) * (1.0/3) * 0; // l
        res += (1-p_) * (1.0/3) * f(min(100, p+q), r+1); // d
        res += (1-p_) * (1.0/3) * 1; // w
    }
    return res;
}

int main() {
    while (cin >> p0 >> q) {
        fill((ld*)begin(dp), (ld*)end(dp), -10);
        ld ans = (f(p0,0)+1) / 3;
        printf("%.10lf\n", (double)ans);
    }
}