#include <iostream>
#include <algorithm>
#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

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

int main() {
    string s;
    int totalSum = 0, countWords = 0;
    while(fin >> s) {
        for (int i = 0; i < s.size(); ++i) {
            if (('a' <= s[i] && s[i] <= 'z') || ('A' <= s[i] && s[i] <= 'Z')) {
                ++totalSum;
            }
        }
        int isNotLetter = 0, wordCount = 1, letter = 0;
        for (int i = 0; i < s.size(); ++i) {
            if (('a' <= s[i] && s[i] <= 'z') || ('A' <= s[i] && s[i] <= 'Z')) {
                letter = 1;
            } else {
                isNotLetter = 1;
            }
            if (isNotLetter == 1 && (('a' <= s[i] && s[i] <= 'z') || ('A' <= s[i] && s[i] <= 'Z')) && letter) {
                wordCount++;
                isNotLetter = 0;
            }
        }
        if (letter == 0) {
            wordCount = 0;
        }
        countWords += wordCount;

    }
    fout << totalSum / countWords;
    return 0;

}