N = int(input())
P = list(map(int,input().split()))
def f(x):
    x = str(x)
    if len(x)==1:return int(x)
    res = 0
    for i in range(len(x)):
        res += int(x[i])
    return f(res)
ans = 1
for i in range(N):
    ans = f(ans*f(P[i]))
print(ans)