import sys
readline=sys.stdin.readline

N=int(readline())
A=map(int,readline().split())
dp=set()
dp.add(next(A))
for a in A:
    prev=dp
    dp=set()
    dp|={i+a for i in prev}
    dp|={i-a for i in prev}
    dp|={i*a for i in prev}
    if a>0:
        dp|={(-i)//a*(-1) for i in dp}
ans=max(dp)
print(ans)