#include<iostream>
using namespace std;
int a[100000];
int main() {
	int n;
	cin >> n;
	int sum = 0;
	for (int i = 0;i < n;i++)
	{
		cin >> a[i];
		sum += a[i];
	}
	int mod = 0;
	int out = 0;
	int sum2=0;
	if (sum <= 9 && sum >= 0) {
		cout << sum;
		return 0;
	}
	for (int i = 0;i <1e18;i++) {

		if (sum <= 9 && sum >= 0) {
			
			if (sum2+sum <= 9 && sum2+sum >= 0) {
				out = mod + sum;
				mod = 0;
				sum = 0;
				
				sum2 = 0;
				break;
			}
			if (sum == 0) {
				sum = sum2;
				sum2 = 0;
				mod = 0;
			}
		}
		
		

		mod += sum %10;
		sum2 = mod;
		sum = sum / 10;
		
		
		
	}
	cout << out;
}