// ConsoleApplication3.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
using namespace std;

int main()
{
    long long int t, a, sum = 0,ans=10,d=0;
    cin >> t;
    while (t--) {
        cin >> a;
        sum += a;
    }
   
    while (sum/10!=0) {
        while (sum!= 0)
        {
            d += sum % 10;
            sum /= 10;

        }
        sum = d;
        d = 0;
    }
    cout << sum;
    return 0;
    
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file