import sys
input = sys.stdin.readline

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

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

A.sort(reverse=True)

X=0
Y=0
for i in range(len(A)):
    if i%2==0:
        X+=A[i]
    else:
        Y+=A[i]

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