#include"fstream.h"

int main()
{
   ifstream f("text.in");
   ofstream o("text.out");
   unsigned long lit=0;
   unsigned int cuv=0, i;
   char l[30];
   while(!f.eof())
   {
      f>>l;
      if(l[0]>='a' && l[0]<='z' || l[0]>='A' && l[0]<='Z')
      {
         cuv++;
         for(i=0;i<strlen(l);i++)
            if(l[i]>='a' && l[i]<='z' || l[i]>='A' && l[i]<='Z')
               lit++;
            else
               if(i<strlen(l)-1)
                  cuv++;
      }
   }
   o<<lit/cuv;
   f.close();
   o.close();
   return 0;
}