n = gets.not_nil!.to_i
a = gets.not_nil!.split.map(&.to_i64).sort
dp = [10_i64**18]*(n+1)
dp[0] = 0

n.times do |i|
  dp[i+2] = [dp[i+2],dp[i]+a[i+1]-a[i]].min if i+2<=n
  dp[i+3] = [dp[i+3],dp[i]+a[i+2]-a[i]].min if i+3<=n
end

puts dp[n]