#include <bits/stdc++.h>

using u32 = uint32_t;
using u64 = uint64_t;
using i32 = int32_t;
using i64 = int64_t;

int main()
{
    std::ios_base::sync_with_stdio(0);

    u32 numbers;
    std::vector<u32> vec;

    std::cin >> numbers;

    for (u32 i = 0; i < numbers; i++)
    {
        int tmp;
        std::cin >> tmp;
        vec.push_back(tmp);
    }

    u32 sum_of_elems = std::accumulate(vec.begin(), vec.end(), 0);

    while (sum_of_elems > 9)
    {
        std::vector<u32> tmp;
        std::string str = std::to_string(sum_of_elems);

        for (u32 i = 0; i < str.size(); i++)
        {
            u32 digit = (u32)str.at(i);
            tmp.push_back(digit);
        }

        sum_of_elems = std::accumulate(tmp.begin(), tmp.end(), 0);
    }
    std::cout << sum_of_elems;

    return 0;
}