#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;

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

ll sum = 0;
void dfs(int p,int c,ll s){
    if(p == 0 && c == 0){
        sum += s;
        return;
    }
    if(p != 0)
    for(int i=0;i<6;i++){
        dfs(p-1,c,s*a[i]);
    }
    if(p == 0 && c != 0)
    for(int i=0;i<6;i++){
        dfs(p,c-1,s*b[i]);
    }
}

int main(void){
    int p,c;
    cin >> p >> c;
    dfs(p,c,1);
    cout <<fixed << setprecision(15)<< 1.*sum/pow(6LL,p+c) << endl;

	return 0;
}