#include <bits/stdc++.h>

using namespace std;

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

string s;
int lung,el,sum=0;

int main()
{
    while(getline(in,s)){
        int i = 0;
        while(i<=s.length()){
            lung = 0;
            while(((int)s[i]>=65 && (int)s[i]<=90) || ((int)s[i]>=97 && (int)s[i]<=122)){
                lung++;
                i++;
            }
            if(lung!=0) sum+=lung, el++;
            i++;
        }
    }
    out << sum / el;
    return 0;
}