n = int(input())
p = list(map(int, input().split()))

k = 1
for i in range(n):
    ps = sum(map(int, str(p[i])))
    if ps == 0:
        print(0)
        exit()
    k *= ps
    k %= 9

if k == 0:
    print(9)
else:
    print(k)