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)
    Q = Q2
print(max(list(Q)))