#include <bits/stdc++.h>
#define FOR(i,bg,ed) for(ll i=(bg);i<(ed);i++)
#define REP(i,n) FOR(i,0,n)
#define MOD 1000000007
#define int long long
using namespace std;
typedef long long ll;
const int INF = 1e9;

int p0, q;
const int ma = 20;

double use(int p, int i);

double unuse(int p, int i)
{
    if (i > ma) return 0.0;
    return 1.0/3.0 + (p/100.0*use(max(0LL,p-q),i+1) + (100.0-p)/100.0*unuse(min(100LL,p+q),i+1))/3.0;
}

double use(int p, int i)
{
    if (i > ma) return 0.0;
    return 1.0/2.0 + (p/100.0*use(max(0LL,p-q),i+1) + (100.0-p)/100.0*unuse(min(100LL,p+q),i+1))/2.0;
}

signed main()
{
    cin >> p0 >> q;
    //cout << unuse(p0, 1) << endl;
    printf("%.10lf\n", unuse(p0, 1));
}