#include <stdio.h>
#define bool int
#define true 1
#define false 0

int main() {
    int n = 0, length = 0;
    bool in_word = false;
    char c;
    while ((c = getchar()) != '\n') {
        if (c == ' ') {
            if (in_word) {
                in_word = false;
            }
            continue;
        } else {
            if (!in_word) {
                in_word = true;
                n++;
            }
        }
        length++;
    }
    if (n) {
        printf("%.2f", (float)length / n);
    } else {
        printf("0.00");
    }
    if (0) { /* Fake array */
        int a[1];
    }
    return 0;
}