1084

#include <iostream>
using namespace std;
int main()
{
	double a;
	double sum = 0;
	for(int i=0; i<12; i++)
	{
		cin>>a;
		sum+=a;
	}
	sum/=12;
	cout.setf(ios::fixed);
	cout.precision(2);
	cout<<"$"<<sum<<endl;
	return 0;
}