def sort(a):
    n = len(a)
    for i in range(n-1):
        k=i
        for j in range(i+1,n):
            if a[k]>a[j]:
                k=j
        a[i],a[k]=a[k],a[i]

    return a
k=int(input())
a=sort(list(map(int,input().split())))
c=len(a)//2
g=a[:c]
b=a[c:]
k=0
m=0
n=0
for i in range(len(g)):
    k+=g[i]
for j in range(len(b)):
    m+=b[j]
n=m-k
print(n)