#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <cstdlib>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional> 
#include <iomanip>
#include <unordered_map>
#include <memory.h>
#include <unordered_set>
#include <fstream>
#include <random>

using namespace std;

int main(void)
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	vector <long long int> v;
	long long int res = 1, t;
	int n;

	cin >> n;

	for (int i = 0; i < n; i++)
	{
		cin >> t;
		v.push_back(t);
	}

	for (int i = 0; i < n; i++)
	{
		long long int val = v[i];
		while (val >= 10)
		{
			long long int temp = val;
			long long int sum = 0;
			while (temp > 0)
			{
				sum += (temp % 10);
				temp /= 10;
			}
			val = sum;
		}
		res *= val;
		val = res;
		while (val >= 10)
		{
			long long int temp = val;
			long long int sum = 0;
			while (temp > 0)
			{
				sum += (temp % 10);
				temp /= 10;
			}
			val = sum;
		}
		res = val;
	}

	cout << res << '\n';

	return 0;
}