#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main ()
{
    ifstream fin ("text.in");
    ofstream fout ("text.out");
    string str;
    int nrca=0,nrcu=0;
    while (!fin.eof()){
    fin>>str;
    //<<"str:"<<str<<"\n";
        int n=str.length();
    ////<<"str:"<<str<<"\n";
    char c;

    //<< " n="<<n;
    for (int i=0;i<n;++i)
    {
        c=str[i];
        if ((65 <= c && 90>=c) || (97 <= c && 122>=c))
        {
            nrca++;
        }
    }
    nrcu++;

    }
    nrca/=nrcu;
    fout<<nrca;
}