#include<iostream>
#include<vector>
#include<string>
#include<array>
#include<algorithm>
#include<list>
#include<cmath>
#include<iomanip>
#include<queue>
#include<functional>
#include<climits>
#include<iterator>
#include<unordered_set>
#include<unordered_map>
#include<map>
#include<set>
#include<typeinfo>
using namespace std;

const double pi=4*atan(1.0);

constexpr long long mod=static_cast<long long>(1e9+7);

using cWeightEdges=vector<vector<pair<int,int>>>;
using cEdges=vector<vector<int>>;

int main() {
	int p,q;
	cin>>p>>q;
	vector<double> dp1(101,0);
	vector<double> dp2(101,0);
	int cnt=0;
	while(1){
		for(int i=0;i<101;++i){
			dp1[i]=double(i)*(1.+dp1[max(0,i-q)])/200.+(100.-double(i))*(1+dp1[min(100,i+q)])/300.;
		}
		++cnt;
		if(cnt>10000)break;
	}
	cout<<fixed<<setprecision(10)<<dp1[p]/3.+1./3.<<endl;
	//system("pause");
	return 0;
}