#include<iostream>
#include <iomanip>
#include<vector>
#include<math.h>

using namespace std;

int N;

int get_mal(vector<int> x) {

    int y = 1;
    for(int i=0; i<x.size(); i++) {
        y *= x[i];
    }
    return y;

}

vector<int> get_num(int x) {
    vector<int> num_array;
    int X = x;
    int keta = 1;
    for(int i = 1; i<99999999; i++) {
        x /= pow(10, i);
        if(x > 0) {
            keta++;
            x = X;
        }
        else {
            x = X;
            break;
        }
    }
    for(int i = keta; i>0; i--) {
        
        int num = x / pow(10, i-1);
        if(x<10) {
            num_array.push_back(X%10);
            break;
        }
        num_array.push_back(num);
        
        x -= num * pow(10, i-1);
    }

    return num_array;
} 

int main() {
    cin >> N;
    vector<int> P;
    int p;
    for (int i=0; i<N; i++) {
        cin >> p;
        P.push_back(p);
    }
    int mal = get_mal(P);
    int sum = 0;
    vector<int> num_array = get_num(mal);
    for(int i=0; i<num_array.size(); i++) {
        sum += num_array[i];
    }

    while (sum > 10) {
        vector<int> v = get_num(sum);
        sum = 0;
        for(int i = 0; i<v.size(); i++) {
            sum += v[i];
        }
    }

    cout << sum << endl;


    return 0;

}