N = int(input())
a = list(map(int,input().split()))
s = set()
s.add(a[0])
for i in range(1,N):
    t = set()
    b = a[i]
    for v in s:
        t.add(v+b)
        t.add(v*b)
        t.add(v-b)
    s = t
print(sorted(s)[-1])