n = int(input())
a = list(map(int, input().split()))
original_sum = sum(abs(x) for x in a)

if n == 0:
    print(0)
    exit()

max_val = max(a)
pos = a.index(max_val)

# Calculate contributions
contributions = [abs(max_val) - abs(x) for x in a]

# Compute max_ending_at_pos (left part)
max_ending = 0
current = 0
for i in range(pos - 1, -1, -1):
    current += contributions[i]
    if current > max_ending:
        max_ending = current

# Compute max_starting_at_pos (right part)
max_starting = 0
current = 0
for i in range(pos + 1, n):
    current += contributions[i]
    if current > max_starting:
        max_starting = current

total_gain = max_ending + max_starting
answer = original_sum + max(total_gain, 0)
print(answer)