function main(input) {
  const args = input.split(' ')
  var N = Number(args[0])
  var L = Number(args[1])
  var azi_sum = 0
  var min_abs = 1000000
  for (var i = 1; i <= N; i++) {
    var azi = L + i - 1
    if (min_abs * min_abs > azi * azi) {
      min_abs = azi
    }
    azi_sum += azi
  }
  azi_sum -= min_abs
  console.log(azi_sum)
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'))
