import sys
sys.setrecursionlimit(10000000)
MOD = 10 ** 9 + 7
INF = 10 ** 15

N = int(input())
A = list(map(int,input().split()))
ans = A[0]
for i in range(1,N):
    if A[i] == 1:
        ans += 1
    elif A[i] > 0:
        ans *= A[i]
    elif A[i] < 0:
        ans -= A[i]
print(ans)