#include <fstream>
#include <cstring>

using namespace std;

ifstream f("text.in");
ofstream g("text.out");

char s[50000],s1[50000],s2[50000],*p,sep[]=",. '/?><\|][{}+=_)(*&^%$#@!`~";

int main()
{
    int cont=0,contl=0,nrl,i;
        while (!f.eof())
        {
            f.getline(s2,50000);
            strcat(s,s2);
            strcat(s," ");
        }
      //  g<<s;
        nrl=strlen(s);
        for (i=0; i<nrl; ++i)
            if ((s[i]>=65 && s[i]<=90) || (s[i]>=97 && s[i]<=122)) contl++;
        p=strtok(s,sep);
        while (p)
        {
            cont++;
            strcat(s1,p);
            p=strtok(NULL," ");
        }
        g<<contl/cont;
    return 0;
}