n = io.read("*n")
t = {}
for i = 1, n do
  table.insert(t, io.read("*n"))
end
table.sort(t)
spos, epos = 1, #t
len = 0
while(spos <= epos) do
  len = len + t[epos] - t[spos]
  spos, epos = spos + 1, epos - 1
end
print(len)