sergo

#include <iostream>

using namespace std;

int main(void) {
    int n;
    cin >> n;
    int cnt = 0, s = 0;
    for (; n != 0; cnt ++) {
        s += n % 10;
        n /= 10;
    }
    cout << (s / (double)cnt) << endl;
    return 0;
}