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

#define MAX 1000000

int main()
{
    ifstream in("text.in");
    ofstream out("text.out");

        char a[MAX], *p;
        in.getline(a,MAX);

        p = strtok (a," ");
    int nr=0,ch=0;
        while(p != NULL) {
            ch+=strlen(p);
        nr++;
            if(!((int)tolower(p[0])>=97&&(int)tolower(p[0])<=122)) {
                ch--;
            }
            if(!((int)tolower(p[strlen(p)-1])>=97&&(int)tolower(p[strlen(p)-1])<=122)) {
                ch--;
            }
             //   cout << strlen(p) << " " << p << endl;
            p = strtok (NULL ," ");
        }
    cout << ch/nr;
    in.close();
    out.close();
    return 0;
}