#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
#include<unordered_map>
#include<unordered_set>
using namespace std;
long long int aa[] = { 2, 3, 5, 7, 11, 13 };
long long int b[] = { 4, 6, 8, 9, 10, 12 };
int main(){
	int p, c;
	cin >> p >> c;
	long long int a = pow(6, p + c);
	double ans = 0;
	for (int i = 0; i < a; i++){
		long long int k = 1LL;
		int d = i;
		for (int j = 0; j < p; j++){
			int ind = d % 6;
			k *= aa[ind];
			d /= 6;
		}
		for (int j = 0; j < c; j++){
			int ind = d % 6;
			k *= b[ind];
			d /= 6;
		}
		long double aa = k;
		aa /= (long double)(a);
		ans += (double)aa;
	}
	printf("%.16f\n", ans);
	return 0;
}