def run(lines, input)
  output = [] of Int32
  pos = 0
  get = ->(x : Char, p : Int32) {
    x == '0' ? lines[lines[pos+p]] : lines[pos+p]
  }
  loop do
    str = "000" + lines[pos].to_s
    case str
    when .ends_with?("1")
      lines[lines[pos+3]] = get.call(str[-3], 1) + get.call(str[-4], 2)
      pos += 4
    when .ends_with?("2")
      lines[lines[pos+3]] = get.call(str[-3], 1) * get.call(str[-4], 2)
      pos += 4
    when .ends_with?("3")
      lines[lines[pos+1]] = input.pop
      pos += 2
    when .ends_with?("4")
      output << get.call(str[-3], 1)
      pos += 2
    when .ends_with?("5")
      if get.call(str[-3], 1) != 0
        pos = get.call(str[-4], 2) 
      else
        pos += 3
      end
    when .ends_with?("6")
      if get.call(str[-3], 1) == 0
        pos = get.call(str[-4], 2) 
      else
        pos += 3
      end
    when .ends_with?("7")
      lines[lines[pos+3]] = (get.call(str[-3], 1) < get.call(str[-4], 2)) ? 1 : 0
      pos += 4
    when .ends_with?("8")
      lines[lines[pos+3]] = (get.call(str[-3], 1) == get.call(str[-4], 2)) ? 1 : 0
      pos += 4
    when .ends_with?("99")
      break
    else
      raise "Invalid instruction"
    end
  end
  {output, lines}
end