def calcs(x,y,ax,ay,bx,by) ((ax-x)*(by-y)-(bx-x)*(ay-y))/2.0 end
def inpf() a=gets.chomp.split(" ").map(&:to_f)end
def inps() a=gets.chomp.split(" ")end  
def copy(a) Marshal.load(Marshal.dump(a)) end
def kaizyo(n)(n < 2)? 1 : (2..n).inject(:*) end
def scount(a) b=na(a.max+1);a.each{|n|b[n]+=1};return b end
def na(n=0,d=0) Array.new(n,d)end
def na2(n=0,m=0,d=0) Array.new(n){Array.new(m,d)}end
def na3(n=0,m=0,l=0,d=0) Array.new(n){Array.new(m){Array.new(l,d)}}end
def bit(n) n.to_s(2).split("").map(&:to_i) end
def inp() a=gets.chomp.split(" ").map(&:to_i)end
@n,@m= inp
d=[]; @m.times{d.push(inp[0])}
d.sort!
min = d[2]-d[0]
now  = min
ind = -1
d.each.with_index do |dd,i|
  if(dd >= 0)
  ind = i 
  break
  end
end
@ans = 99999999999
def lser(x,s,a)
  return if(x<0)
  if(s == @n)
    @ans = [@ans,a[x].abs].min
  end
  lser(x-1,s+1,a)
  @ans = [@ans,a[x].abs+(a[x] - a[x+@n-1]).abs].min if(a[x+@n-1] != nil) 
end
def rser(x,s,a)
  return if(x >= @n)
  if(s == @n)
    @ans = [@ans,a[x].abs].min
  end
  lser(x+1,s+1,a)
  @ans = [@ans,a[x].abs+(a[x] - a[x-@n+1]).abs].min if(a[x-@n+1]!= nil) 
end
t=0
t = 1 if(d[ind] == 0)
lser(ind,t,d)
rser(ind,t,d)
p @ans
=begin
=end