# coding: utf-8

def readData():
    n   = input()
    a_n = []
    while len(a_n) != n:
        a_n = map(int, raw_input().split())

    return n, a_n

def caluclateCards(n, a_n):
    ans = 0
    for i in xrange(n):

        if i == 0:
            ans = abs(a_n[i])
        else:
            if ans == 0:
                ans += abs(a_n[i])
            else:
                if a_n[i] == 0 or abs(a_n[i]) == 1:
                    ans += abs(a_n[i])
                else:
                    ans *= abs(a_n[i])

    print ans

if __name__ == "__main__":
    n, a_n = readData()
    caluclateCards(n, a_n)