n = int(input())
a = list(map(int, input().split()))

original_sum = sum(abs(x) for x in a)

if n == 0:
    print(0)
else:
    gm = max(a)
    pos = a.index(gm)
    delta = [abs(gm) - abs(x) for x in a]
    
    # Compute max_left (from pos to 0)
    max_left = 0
    current_sum = 0
    for i in range(pos, -1, -1):
        current_sum += delta[i]
        if current_sum > max_left:
            max_left = current_sum
    
    # Compute max_right (from pos to n-1)
    max_right = 0
    current_sum = 0
    for i in range(pos, n):
        current_sum += delta[i]
        if current_sum > max_right:
            max_right = current_sum
    
    gain = max(0, max_left + max_right)
    print(original_sum + gain)