#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int p0, q;
const int R = 10000;
double dp[R][101];
double f(int x, int y){
    if(x == R)return 0;
    if(dp[x][y] > -0.5)return dp[x][y];
    double &res = dp[x][y];
    double p = y / 100.0;
    res = p/2.0 + 1 / 3.0*(1 - p);
    res += p / 2.0*f(x + 1, max(y - q, 0));
    res += (1 - p) * 1 / 3.0*f(x + 1, min(y + q, 100));
    return res;
}


int main(){
    
    cin >> p0 >> q;
    rep(i, R)rep(j, 101)dp[i][j] = -1;
    double ans = 1.0 / 3.0;
    ans += 1.0/3*f(0, p0);
    cout << setprecision(20) << ans << endl;
}