#include <fstream>
#include <iostream>
#include <ctype.h>
#include <string.h>
using namespace std;
ifstream in("text.in");
ofstream out("text.out");
int main()
{
    string s;
    int litere = 0, i, cuvinte = 0, total_litere = 0;
    while(in >> s) {
        for(i = 0; i <= s.length(); i++) {
            if(isalpha(s[i])) litere++;
            else if(litere > 0) {
                total_litere = total_litere + litere;
                cuvinte++;
                litere = 0;
            }
        }
    }
    out << total_litere / cuvinte;
    return 0;
}