function Main(input) {
  var N = parseInt(input.split(" ")[0]);
  var L = parseInt(input.split(" ")[1]);
  var aji = [];
  for(var i = 1; i < N + 1; i++){
    aji.push(L + i - 1);
  }
  aji.sort(function(a, b){
  	return Math.abs(a) - Math.abs(b);
  });
  var output = 0;
  for(var i = 0; i < aji.length; i++){
    output += parseInt(aji[i]);
  }
  output = output - parseInt(aji[0]);
  console.log(output);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));
