from functools import reduce
from operator import mul
from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    N = int(input())
    P = map(int, input().split())

    def func(n):
        d, ret = 1, 0
        while 1:
            while d > 0:
                d, m = divmod(n, 10)
                ret += m
                n = d
            if ret < 10:
                return ret
            d, n = 1, ret
            ret = 0

    p = [func(i) for i in P]
    k = reduce(mul, p)
    ans = 10
    while ans > 9:
        ans = func(k)
        k = ans
    print(ans)


main()