#include <cstring>
#include <cstdio>
#include <cstdint>


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

    uint32_t len = 0;
    uint32_t words = 0;
    char word[1024 * 1024 + 1] = {0};
    while(true) {
        scanf("%*[^a-zA-Z]");
        if(scanf("%[a-zA-Z]", word) == EOF) break;
        len += strlen(word);
        words++;
    }

    printf("%u", len / words);

    return 0;
}