#include using namespace std; using ll = long long; using ld = long double; int p0, q; const int LIM = 50; 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); } }