#include<iostream>
#include<fstream>
#include<cstring>
using namespace std;
ifstream fin("text.in");
ofstream fout("text.out");
int n,i;
char s[1000];

int main ()
{
    int cnt,numar,suma,x;
    int st,dr;
    suma=0; numar=0;
    while (fin>>s)
    {
        x=strlen(s);
        if (x>1)
        {
            cnt=0;
            for (i=1;i<=x;i++)
            {
                if (!((s[i]-'a'<=25 && s[i]-'a'>=0) || (s[i]-'A'<=25 && s[i]-'A'>=0)))
                  {
                     cnt++;
                     if (cnt==1)
                     {
                         st=i;
                         suma=suma+i;
                     }

                     else
                     {
                         dr=i;
                         suma=suma+(dr-st-1);
                         st=dr;
                     }

                  }
            }
             numar=numar+cnt;
        }
    }
    int cece;
    cece=suma/numar;
    fout<<cece<<"\n";
    fout.close();
    fin.close();
    return 0;
}