#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) REP((i),0,(n))
#define RREP(i,a,b) for(int i=(int)(a);i>=(int)(b);i--)
#define rrep(i,n) RREP(i,n,0)
#define each(it,X) for(__typeof((X).begin())  it=(X).begin();it!=(X).end();it++)
#define all(v) ((v).begin(),(v).end())
#define fi first
#define se second
#define pb push_back
typedef pair<int,int>pr;
typedef vector<int>vi;
typedef vector<vi>vvi;
const int INF=1070000000ll;
const int mod=1000000007ll;

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

signed main(){
    int p,c;cin>>p>>c;

    map<int,int>prev;
    prev[1]=1;

    rep(i,p){
        map<int,int>next;
        each(it,prev){
            rep(j,6){
                next[it->first*a[j]]+=it->second;
            }
        }
        prev=next;
    }

    rep(i,c){
        map<int,int>next;
        each(it,prev){
            rep(j,6){
                next[it->first*b[j]]+=it->second;
            }
        }
        prev=next;
    }


    int d=1;rep(i,p+c)d*=6;

    int ret=0;
    each(it,prev){
        ret+=it->first*it->second;
    }

    cout<<setprecision(10);
    cout<<1.0*ret/d<<endl;
    return 0;
}