n = int(input())
c = list(map(int, input().split()))
c.sort()
sei = [i for i in c if i >= 0]
sei.sort()
hu = [i for i in c if i < 0]
hu.sort()
a, b = 0, 0
for i in range(len(sei)):
    if i % 2:
        b += sei[i]
    else:
        a += sei[i]
seile = len(sei)
for i in range(len(hu)):
    if (i + seile) % 2:
        b += hu[i]
    else:
        a += hu[i]
print(abs(abs(a) - abs(b)))