#include <bits/stdc++.h>
using namespace std;

#define int long long
int p[6]={2,3,5,7,11,13},c[6]={4,6,8,9,10,12};
using ld=long double;

signed main(){
  int P,C;cin>>P>>C;
  ld A=pow(6,P+C);
  map<int,int> dp;
  dp[1]=1;
  stack<int> sta;
  while(P--){
    for(auto tmp:dp)sta.push(tmp.first);
    while(sta.size()){
      int tmp=sta.top();sta.pop();
      for(int j=0;j<6;j++){
        dp[tmp*p[j]]+=dp[tmp];
      }
      dp.erase(tmp);
    }
  }

  while(C--){
    for(auto tmp:dp)sta.push(tmp.first);
    while(sta.size()){
      int tmp=sta.top();sta.pop();
      for(int j=0;j<6;j++){
        dp[tmp*c[j]]+=dp[tmp];
      }
      dp.erase(tmp);
    }
  }
  ld sum=0;
  for(auto tmp:dp)sum+=tmp.first*tmp.second;
  cout<<fixed<<setprecision(12)<<sum/A<<endl;
}