from collections import deque
n = int(input())
c = sorted(map(int, input().split()))
s = sum(c)

q = deque(c)
a = 0
b = s
if b >= 0:
    while q:
        v = q.pop()
        b -= v
        if q:
            q.pop()
    if b < 0:
        b = 0
    elif b > s:
        b = s
    a = s - b
    print(a - b)
else:
    while q:
        v = q.popleft()
        b -= v
        if q:
            q.popleft()
    if b > 0:
        b = 0
    elif b < s:
        b = s
    a = s - b
    print(-a - -b)