#include <iostream>
#include <vector>

using namespace std;

int main() {
	int n;
	cin >> n;
	vector<long long> vec;
	long long sum = 0;
	for (int i = 0; i < n; i++) {
		long long t;
		cin >> t;
		vec.push_back(t);
	}

	for (int i = 0; i < n; i++) {

		while (vec[i] / 10 != 0) {

			long long sum = 0;
			while (vec[i] != 0) {
				sum += (vec[i] % 10);
				vec[i] = vec[i] / 10;
			}

			vec[i] = sum;
		}
	}
	long long f = 0;
	for (auto i : vec) {
		f += i;
	}

	while (f / 10 != 0) {

		long long sum = 0;
		while (f != 0) {
			sum += (f % 10);
			f = f / 10;
		}

		f = sum;
	}
	cout << f << endl;
	return 0;
}