N = int(input())
P = list(map(int, input().split()))

ans = 1
def f(n:int):
    res = 0
    for s in str(n):
        res += int(s)
        if res >= 10:
            res -= 9
    return res

for p in P:
    ans *= f(p)
    ans = f(ans)

print(ans)