N = int(input())
A = list(map(int, input().split()))

if sum(A) < 0:
    A = [-a for a in A]

A.sort()
X = Y = 0
f = 1
while A:
    if f:
        X += A.pop()
    else:
        Y += A.pop()
    f = 1 - f

print(abs(X)-abs(Y))