n = int(input())
a = list(map(int, input().split()))
m = max(a)
sum_abs = sum(abs(x) for x in a)
b = [abs(m) - abs(x) for x in a]

# Kadane's algorithm to find maximum subarray sum
max_current = max_subarray = b[0]
for num in b[1:]:
    max_current = max(num, max_current + num)
    max_subarray = max(max_subarray, max_current)

max_gain = max(0, max_subarray)
print(sum_abs + max_gain)