#include <iostream>
#include <vector>
#include <utility>
#include <map>
#include <algorithm>
#include <queue>
#include <cmath>

using namespace std;

int main() {
    int n;
    cin >> n;
    unsigned long long k = 1;
    for (int i=0; i<n; i++) {
        unsigned long long p;
        cin >> p;
        k *= p;
    }

    long long ans = 0;
    while(k>0) {
        ans += (k%10);
        k/=10;
    }
    cout << ans << endl;
}