#include <bits/stdc++.h>

using namespace std;

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

string s;
int medie,cate,i,poz,sz,k;
bool ok;

int main()
{
    while(getline(f, s))
    {
        sz = s.size();
        ok = k = 0;
        for(i = 0; i < sz; ++ i)
        {
            if(isalpha(s[i]))
            {
                ++ k;
                ok = 1;
            }
            else
            {
                if(ok)
                {
                    medie += k;
                    ++ cate;
                }
                ok = 0;
                k = 0;
            }
        }
        if(ok)
        {
            medie += k;
            ++ cate;
        }
    }
    if(!cate)
        g << 0;
    else
        g << medie / cate;
}