#include<bits/stdc++.h>
using namespace std;
int main(){
	float n,maxx;
	cin>>n;
	cin>>max;
	max*=6.5328;
	for(int i=2;i<=12;i++){
		cin>>ai;
		maxx=max(ai*12,maxx)
	}
	cout<<maxx;
}
/**************************************************************
	Problem: 2031
	User: wangyiyang
	Language: C++
	Result: Compile Error
****************************************************************/