N = int(input())
A = list(map(int, input().split()))
Q = {A[0]}
for a in A[1:]:
    Q2 = set()
    while Q:
        x = next(iter(Q))
        Q.remove(x)
        Q2.add(x + a)
        Q2.add(x - a)
        Q2.add(x * a)
        if a != 0:
            Q2.add(x // a)
    Q = Q2
print(max(list(Q)))