#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int p0; int q;
	while(~scanf("%d%d", &p0, &q)) {
		vector<double> dp, ndp(101);
		double ans = 1. / 3;
		ndp[p0] = 1. / 3;
		while(accumulate(ndp.begin(), ndp.end(), 0.) > 1e-15) {
			dp.swap(ndp);
			ndp.assign(101, 0);
			rep(p, 101) {
				double x = dp[p];
				if(x < 1e-99) continue;
				//使う
				double y = x * p / 100;
				ans += y / 2;
				ndp[max(0, p - q)] += y / 2;
				//使わない
				double z = x - y;
				ans += z / 3;
				ndp[min(100, p + q)] += z / 3;
			}
		}
		printf("%.10f\n", ans);
	}
	return 0;
}