<?php
    /*
        Problem URL : http://agc001.contest.atcoder.jp/tasks/agc001_b

        Score  :
        Result :
        Time   : ms
        Memory : KB
     */

    ini_set('display_errors', 'Off');
    ini_set('error_reporting', E_ALL & ~E_NOTICE);

    fscanf(STDIN, "%d %d", $N, $X);

    $a = $X;
    $b = 0;
    $direction = "b";
    $answer = 0;

    // そこを通ったか
    $m[$a][$b] = -1;
    // 航跡
    $n[$a][$b] = "";

    while($m[$X][0] < 0) {
        switch($direction) {
            case "a":
                $a++;
                $answer++;
                break;

            case "b":
                $b++;
                $answer++;
                break;

            case "-ab":
                $a--;
                $b--;
                $answer++;
                break;

        }
        // echo "{$direction} a:{$a} b:{$b} ans:{$answer}\n";

        // インクリメント
        $m[$a][$b]++;
        // 右の壁にぶつかった
        if ($a == $b) {
            $direction = "a";
        }
        // 下の壁にぶつかった
        elseif ($a == $N) {
            $direction = "-ab";
        }
        // 左の壁にぶつかった
        elseif ($b == 0) {
            $direction = "b";
        }
        // すでに航跡がある
        elseif ($m[$a][$b] > 0) {
            // echo "aru {$n[$a][$b]}\n\n";
            if ($direction == "b" && $n[$a][$b] == "a") {
                $direction = "-ab";
            }
            elseif ($direction == "b" && $n[$a][$b] == "-ab") {
                $direction = "a";
            }
            elseif ($direction == "-ab" && $n[$a][$b] == "b") {
                $direction = "a";
            }
            elseif ($direction == "-ab" && $n[$a][$b] == "a") {
                $direction = "b";
            }
            elseif ($direction == "a" && $n[$a][$b] == "b") {
                $direction = "-ab";
            }
            elseif ($direction == "a" && $n[$a][$b] == "-ab") {
                $direction = "b";
            }
        }
        $n[$a][$b] = $direction;
    }
    // echo "direct:{$direction}\n";
    // echo "ENDE\n";

    echo $answer . "\n";
