#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000

int Pdice[6] = { 2, 3, 5, 7, 11, 13 };
int Cdice[6] = { 4, 6, 8 ,9, 10 ,12 };

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
	int P, C;
	cin >> P >> C;
	double ans = 0;
	double sum = 0;
	int bit6 = 1;
	rep(i, P + C) bit6 *= 6;
	rep(i, bit6) {
		double tmp = 1;
		int tmpbit = i + 1;
		rep(j, P) {
			tmp *= Pdice[tmpbit % 6];
			tmpbit /= 6;
		}
		rep(j, C) {
			tmp *= Cdice[tmpbit % 6];
			tmpbit /= 6;
		}
		sum += tmp;
	}
	//cout << sum << endl;


	
	cout << fixed;
	cout << std::setprecision(10) << sum / bit6 << endl;
	

    return 0;
}