#include <cstdio>
#include <cstring>
#include <cctype>

using namespace std;

char BUFF[2000000];

int main() {
    freopen("text.in", "r", stdin);
    freopen("text.out", "w", stdout);

    int i, j, L, wordCount = 0, wordSum = 0;

    while(gets(BUFF + 1) != NULL) {
        gets(BUFF + 1);
        L = strlen(BUFF + 1);

        for(i = 1; i <= L; i++) {
            for(j = i; j <= L && isalpha(BUFF[j]); j++);
            if(j > i) {
                wordCount++;
                wordSum += j - i;
                i = j - 1;
            }
        }
    }

    printf("%d\n", wordSum / wordCount);
    return 0;
}