// infoarena: problema/text //
#include <fstream>
#include <cstring>
using namespace std;

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

int num,sum,in_word,s;
char c;

int main()
{
    in_word = false;
    while(in.good())
    {
        c = in.get();
        if((c>='a' && c<='z') || (c>='A' && c<='Z'))
        {
            if(in_word)
                ++ s;
            else
            {
                in_word = true;
                s = 1;
            }
        }
        else
        {
            if(s)
            {
                ++ num;
                sum += s;
            }

            s = 0;
            in_word = false;
        }
    }
    //out<<sum<<' '<<num<<'\n';
    out<<sum/num;
    return 0;
}