N = int(input())
C = list(map(int, input().split()))
if sum(C) < 0:
    for i in range(N):
        C[i] = -C[i]

a, b = 0, 0
C.sort(reverse=True)
for i in range(N):
    if i % 2 == 0:
        a += C[i]
    else:
        b += C[i]

print(abs(a) - abs(b))