#include<iostream>
#include<fstream>
#include<string.h>
using namespace std;

int main()
{   ifstream f("bac.in");
    ofstream g("text.out");
    char s[1050000];
    int l=0,nr=0,sum=0;
    while(f.get(s,1050000))
    {for(int i=0;s[i];i++)
        if(s[i]>=65&&s[i]<=90||s[i]>=97&&s[i]<=122)
        l++;
        else if(l)
            {sum=sum+l;nr++;l=0;}
    if(l)
    {
        sum+=l;nr++;
    }
    }
    g<<sum/nr;
    f.close();
    g.close();
}