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

#define REP(i,n) for(int i=0;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<29
#define LINF LLONG_MAX/3
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define ALL(v) (v).begin(),(v).end()
#define debug(x) cerr<<#x<<":"<<x<<endl
#define debug2(x,y) cerr<<#x<<","<<#y":"<<x<<","<<y<<endl
#define CININIT cin.tie(0),ios::sync_with_stdio(false)
template<typename T> ostream& operator<<(ostream& os,const vector<T>& vec){ os << "["; for(const auto& v : vec){ os << v << ","; } os << "]"; return os; }

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

int p0,q;
double memo[124][100];

double dfs(int p,int depth){
    if(depth > 50) return 1;
    if(memo[p][depth]!=0) return memo[p][depth];
    if(depth==0){
        return memo[p][depth] = (1 + dfs(min(100,p),depth+1)) / 3.0;
    }

    double ret=0;
    ret += (p/100.0) * (1 + dfs(max(0,p-q),depth+1)) / 2.0;
    ret += ((100-p)/100.0) * (1 + dfs(min(100,p+q),depth+1)) / 3.0;
    return memo[p][depth] = ret;
}

int main(){
    CININIT;
    cin>>p0>>q;

    printf("%.20f\n",dfs(p0,0));
}