INF = 10 ** 9
n,m = gets.split.map(&:to_i)
l, r = 2.times.map {
  a = Array.new(m+1,INF)
  a[0] = 0
  a
}

d = m.times.map {  gets.to_i  }
d.select {|v| v >= 0}.sort.take(n).each_with_index {|v,i|
  r[i+1] = v
}
d.select {|v| v < 0}.map {|v| -v }.sort.take(n).each_with_index {|v,i|
  l[i + 1] = v
}

puts (0..n).inject(INF) { |s,i|
  j = n - i
  [s, l[j] * 2 + r[i], l[j] + r[i]* 2].min
}