#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>

int main(void)
{
  ifstream fi("luku.dat");  if ( !fi ) return 1; //ak tj
  double i,j = 0;                           //ak tj
  double summa = 0;                         //ak tj
  double k_a;                               //ak tj

  while ( fi ) {                            //ak tj
    if ( !(fi >> i) ) break;                //ak tj
    summa = summa + i;                      //ak tj
    j++;                                    //ak tj
   }

  fi.close();
  if ( j != 0 )                            // vl
    k_a = summa/j;                             //ak tj
  cout << setprecision(3) << setiosflags(ios::showpoint|ios::fixed)
//     << d(5,3)
       << k_a << endl; //ak tj
//  printf("5.3%lf\n",k_a);
  return 0;
// printf("%p",p);
// cPiste p;   cout << p;
// Teht 11: cout << "(" << x << "," << y << ")" << endl;
}