#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <vector>
#include <queue>
#include <string>
#include <functional>
#include <iostream>


using namespace std;
 
//namaega184 
 
int main(){
	int p,c;scanf("%d%d",&p,&c); 
	int a[10]={2,3,5,7,11,13},b[10]={4,6,8,9,10,12};
	int num=1;
	for(int i=0;i<p+c;i++)num*=6; 
	vector<long long> v;if(p){v.assign(a,a+6);p--;} 
	for(int i=0;i<p;i++){
		vector<long long> tmp;
		for(int j=0;j<v.size();j++){
			for(int k=0;k<6;k++)tmp.push_back(v[j]*a[k]);
		} 
		v=tmp;
	}
	long long sum=0;
	if(v.size()==0){v.assign(b,b+6);c--;}
	for(int i=0;i<c;i++){
		vector<long long> tmp;
		if(c>0)
		for(int j=0;j<v.size();j++){
			for(int k=0;k<6;k++)tmp.push_back(v[j]*b[k]);
		}
		else{ 
		for(int j=0;j<v.size();j++){
			for(int k=0;k<6;k++)sum+=v[j]*b[k];
		}break;
		} 
		v=tmp;
	}
	 
	//for(int i=0;i<v.size();i++)sum+=v[i];
	//printf("%lld.%lld\n",sum/num,(long long)((double)(sum%num)/num*10000000000L)); 
	printf("%.10f\n",(double)sum/num);
	return 0; 
}