import sys

def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))

def main():
    def div(a,b):
        res=abs(a)//abs(b)
        coff=(a*b>0)*2-1
        return coff*res
    n=II()
    aa=LI()
    now=set()
    now.add(aa[0])
    for a in aa[1:]:
        nxt=set()
        for s in now:
            nxt.add(s+a)
            nxt.add(s-a)
            nxt.add(s*a)
            if a!=0:nxt.add(div(s,a))
        now=nxt
    print(max(now))

main()