n = int(input())
C = list(map(int, input().split()))

s = sum(C)
if s < 0:
    C = [-c for c in C]

import heapq
q = []
heapq.heapify(q)
for c in C:
    heapq.heappush(q, -c)
a = 0
b = 0
for i in range(n):
    v = -heapq.heappop(q)
    if i%2 == 0:
        a += v
    else:
        b += v
print(abs(a)-abs(b))