POJ--1004

/*
POJ1004
sxr
2020.1.11
*/

#include 
#include 
using namespace std;

int main(void)
{
     
	double aver = 0.0;
	double s[12] = {
      0 };
	for (int i = 0; i < 12; i++)
		cin >> s[i];
	for (int j = 0; j < 12; j++)
	{
     
		aver += s[j];
	}
	aver = aver / 12;
	cout << "$" << setiosflags(ios::fixed) << setprecision(2) << aver << endl;
	system("pause");
	return 0;
}