#include <iostream>
using namespace std;
using ll = long long;
int main()
{
constexpr ll OFFSET=1e10;
ll N;
cin >> N;
ll sum = 0;
for(ll i = 0; i < N; i++){
long double a;
cin >> a;
sum += static_cast<ll>(a*OFFSET);
}
string s = to_string(sum %OFFSET);
const int size = s.size();
for(int i = 0; i < 10-size; i++){
s.push_back('0');
}
cout << sum / OFFSET << "." << s << endl;
return 0;
}