#include <bits/stdc++.h>

using namespace std;

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

string text;

long long int lt = 0;
long long int nr = 0;
long long int many = 0;

int main()
{
    while(in>>text)
    {
        many = 0;
   for(unsigned int i=0;i<text.size();i++)
    if(((text[i]>='a')&&(text[i]<='z')) || ((text[i]>='A')&&(text[i]<='Z')))
        many++;
    else
    {
       if(many)
        {
            nr++;
            lt+=many;
            many = 0;
        }
    }
            if(many)
                {
                    nr++;
                    lt+=many;
                    many = 0;
                }
    }
    out<<lt/nr<<'\n';
    out.close();
    return 0;
}