def digit_sum(n):
    res = sum(map(int, str(n)))
    while res >= 10:
        n = res
        res = 0
        while n > 0:
            res += n % 10 
            n //= 10
    return res

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

ans = digit_sum(P[0])
for i in range(1, N):
    ans *= digit_sum(P[i])
    if i % 20 == 0:
        ans = digit_sum(ans)
ans = digit_sum(ans)

print(ans)