#include <iostream>
using namespace std;
const int N = 1e5 + 5;
int main() {
	int a[N];
	int n;
	cin >> n;

	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	long long sum = 0;
	for (int i = 0; i < n; i++) {
		sum += a[i];
	}
	int x = 0;
	while (sum >= 10) {
		x = sum % 10;
		sum = sum / 10;
		sum += x;
		
	}

	cout << sum;
	return 0;
}