#include <iostream>
using namespace std;

int main ()
{
    double x1,x2,x3,x4,x5,x6,MO;
    cin>>x1>>x2>>x3>>x4>>x5>>x6;
    while ((x1<0) || (x1>100))
    {
          cin>>x1;}
          while ((x2<0) || (x2>100))
          {
                cin>>x2;}
                while ((x3<0) || (x3>100))
                {
                      cin>>x3;}
                      while ((x4<0) || (x4>100))
                      {
                            cin>>x4;}
                            while ((x5<0) || (x5>100))
                            {
                                  cin>>x5;}
                                  while ((x6<0) || (x6>100))
                                  {
                                        cin>>x6; }
                                        MO=(x1+x2+x3+x4+x5+x6)/6.0;
                                        cout<<MO<<endl;
                                        system ("pause");
                                        return 0;
                                        }