#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-9;
const ll mod=1e9+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

int A,B,a[6]={2,3,5,7,11,13},b[6]={4,6,8,9,10,12};
long double res=0,t=1,M=1;

void dfs(int I){
	if(I==A+B){
		res+=t/M;
		return;
	}
	for(int i=0;i<6;i++){
		ll T=(I<A?a[i]:b[i]);
		t*=T;
		dfs(I+1);
		t/=T;
	}
}

int main(){
	cin>>A>>B;
	for(int i=0;i<A+B;i++) M*=6;
	dfs(0);
	cout<<syosu(11)<<res<<endl;
}