#include <string.h>
#include <stdio.h>
#include <algorithm>
using namespace std;


FILE *in=fopen("text.in","r"),*out=fopen("text.out","w");
long long cr=0,cuv=0;

void _read()
{
  char ch;

  while(!feof(in))
  {
   fscanf(in,"%c",&ch);

   if( strchr("!.? ,", ch )== NULL )
    {
    cuv++;

      while( strchr("!.? ,",ch )== NULL &&!feof(in))
       {
         if( (ch>='a' && ch<='z') || (ch>='A' && ch<='Z'))
           cr++;

        fscanf(in,"%c",&ch);
       }
   }

  }



}

int main()
{
 _read();


 fprintf(out,"%lld",cr/cuv);

return 0;
}