#include <cstdio>
#include <array>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
using namespace std;
int main() {
    int p, q; scanf("%d%d", &p, &q);
    double ans = 1/3.;
    array<double,101> cur = {}; cur[p] = 1/3.;
    repeat (iteration,10000) {
        array<double,101> nxt = {};
        repeat (i,101) {
            // use
            ans += 1/2. * cur[i] * i/100.;
            nxt[max(0, i-q)] += 1/2. * cur[i] * i/100.;
            // don't
            ans += 1/3. * cur[i] * (100-i)/100.;
            nxt[min(100, i+q)] += 1/3. * cur[i] * (100-i)/100.;
        }
        cur.swap(nxt);
    }
    printf("%.12lf\n", ans);
    return 0;
}