n = gets.to_i
a = gets.split.map(&:to_i).sort
dp = Array.new(n).map{Array.new(3,10**15)}
dp[0][1] = 0
(1...n).each do |i|
    dp[i][0] = (dp[i-1][1] < dp[i-1][2] ? dp[i-1][1] : dp[i-1][2])+a[i]-a[i-1]
    dp[i][1] = dp[i-1][0]
    dp[i][2] = dp[i-1][1]+a[i]-a[i-1]
end
puts dp[n-1][0]