#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define R cin>>
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return x>=0&&x<n&&y>=0&&y<m;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
typedef pair<int,int> P;

double ans=0,q;
int p,c;
int a[6]={2,3,5,7,11,13},b[6]={4,6,8,9,10,12};

void dfs(int x, int y, double d) {
  if(x==0 && y==0) {
    ans+=q*d;
    return;
  }
  if(x) {
    rep(i,6) dfs(x-1,y,d*a[i]);
  } else {
    rep(i,6) dfs(x,y-1,d*b[i]);
  }
}

int main() {
  cin >> p >> c;
  q=1;
  rep(i,p+c) q/=6;
  dfs(p,c,1);
  printf("%.10f\n",ans);
  return 0;
}