/* This program reads in int's and prints out
   the average of the values read in. */
#include <iostream>
using namespace std;

int main()
{
  double total = 0.0;
  int count = 0, next;
  while(cin >> next)
  {
    total += next;
    ++count;
  }
  if (count == 0)
  {
    cerr << "Error!  No data entered!" << endl;
    return 1;
  }
  else
  {
    cout << total/count << endl;
    return 0;
  }
}