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

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int p, c;
	cin >> p >> c;
	vector<int> ov{2, 3, 5, 7, 11, 13}, ev{4, 6, 8, 9, 10, 12};
	ll h = 1;
	rep(i, p + c) h *= 6;
	long double s = 0;
	function<void(int, ll)> f = [&](int i, ll m)
	{
		if(i == p + c) {
			s += (long double)m / h;
			return;
		}
		if(i < p) {
			rep(j, 6) f(i + 1, m * ov[j]);
		}
		else {
			rep(j, 6) f(i + 1, m * ev[j]);
		}
	};
	f(0, 1);
	cout << fixed << setprecision(12) << s << endl;
}