main = getLine >> getLine >>= print . foldl1 cardf . map read . words

cardf acc n
 | n<0 = if acc < 0 then acc * n else acc - n
 | n==0 = if acc < 0 then 0 else acc
 | n==1 = acc + 1
 | n>=2 = if acc <= 1 then acc+n else acc * n