#include <bits/stdc++.h>
using namespace std;

#define FOR(i,l,r) for(int i = (l);i < (r);i++)
#define ALL(x) (x).begin(),(x).end()
template<typename T> void chmax(T& a,const T& b){if(a < b) a = b;}
template<typename T> void chmin(T& a,const T& b){if(b < a) a = b;}
typedef long long ll;

double dp [101] [101];
int P,Q;

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin >> P >> Q;

	double ans = 1.0 / 3.0;
	dp [1] [P] = 1.0 / 3.0;
	FOR(i,1,100){
		for(int j = 0;j <= 100;j++){
			if(dp [i] [j] == 0.0) continue;
			ans += dp [i] [j] * (j / 100.0) / 2.0;
			ans += dp [i] [j] * (1.0 - j / 100.0) / 3.0;
			dp [i + 1] [min(j + Q,100)] += dp [i] [j] * (1.0 - j / 100.0) / 3.0;
			dp [i + 1] [max(j - Q,0)] += dp [i] [j] * (j / 100.0) / 2.0;
		}
	}

	cout << fixed << setprecision(10) << ans << endl;

	return 0;
}