import sys
input = sys.stdin.readline

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

if sum(c)<0:
    c = list(map(lambda x: -x, c))

c.sort(reverse=True)
a, b = 0, 0

for i in range(N):
    if i%2==0:
        a += c[i]
    else:
        b += c[i]

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