# -*- coding: utf-8 -*-
def seach(ary, ki)
  for i in 0..ary.length-1
    if ary[i] <= ki && ki <= ary[i+1]
      if ki - ary[i] < ary[i+1] - ki
        return ki - ary[i]
      else
        return ary[i+1] - ki
      end
    end
  end
end   

while true
  d = gets.chomp.to_i #??¨???
  

  if d == 0
    break
  end

  n = gets.chomp.to_i #????????°
  m = gets.chomp.to_i #??¨?????°

  dAry = [] #????????????
  dAry[0] = 0
  for i in 1..n-1
    dAry[i] = gets.chomp.to_i
  end
  dAry[dAry.length] = d
  dAry = dAry.sort

  kAry = [] #?????????
  for i in 0..m-1
    kAry[i] = gets.chomp.to_i
  end

  sum = 0
  kAry.each do |i|
    sum += seach(dAry, i)
  end

  puts sum

end