#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <utility>
#include <cstring>
#include <cmath>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
using namespace std;

#define rep(i,n) for(int i=0; i<n; i++)
typedef long long ll;
typedef pair<int,int> pii;

int p[6] = {2, 3, 5, 7, 11, 13};
int q[6] = {4, 6, 8, 9, 10, 12};
int P, C;

double solve(int a, int b) {
	if(a==0 && b==0) {
		return 1LL;
	}
	double sum = 0.0;
	if(a==0) {
		rep(i, 6) {
			sum += solve(0, b-1) * q[i];
		}
		sum /= 6.0f;
	}
	else {
		rep(i, 6) {
			sum += solve(a-1, b) * p[i];
		}
		sum /= 6.0f;
	}
	return sum;
}	

int main() {
	cin >> P >> C;
	printf("%.10lf\n", solve(P, C));
	return 0;
}