#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> P;

#define EACH(i,a) for (auto& i : a)
#define FOR(i,a,b) for (ll i=(a);i<(b);i++)
#define RFOR(i,a,b) for (ll i=(b)-1;i>=(a);i--)
#define REP(i,n) for (ll i=0;i<(n);i++)
#define RREP(i,n) for (ll i=(n)-1;i>=0;i--)
#define debug(x) cout<<#x<<": "<<x<<endl
#define pb push_back
#define ALL(a) (a).begin(),(a).end()

const ll linf = 1e18;
const int inf = 1e9;
const double eps = 1e-12;
const double pi = acos(-1);

template<typename T>
istream& operator>>(istream& is, vector<T>& vec) {
    EACH(x,vec) is >> x;
    return is;
}
template<typename T>
ostream& operator<<(ostream& os, vector<T>& vec) {
    REP(i,vec.size()) {
        if (i) os << " ";
        os << vec[i];
    }
    return os;
}
template<typename T>
ostream& operator<<(ostream& os, vector< vector<T> >& vec) {
    REP(i,vec.size()) {
        if (i) os << endl;
        os << vec[i];
    }
    return os;
}

int p0, q;
map<int, map<int, double>> memo;
double battle(int p, int turn) {
    if (turn >= 10000) return 0;
    if (memo[p].count(turn) > 0) return memo[p][turn];
    double per = p / 100.;
    double res = 0;
    res += 1./2 * per;
    res += 1./3 * (1-per);
    res += 1./2 * per * battle(max(0, p-q), turn+1);
    res += 1./3 * (1-per) * battle(min(100, p+q), turn+1);
    return memo[p][turn] = res;
}
int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    cin >> p0 >> q;
    cout << fixed << setprecision(12);
    double ans = 1./3 + 1./3 * battle(p0, 0);
    cout << ans << endl;
}