#nullable enable

#region
var _input = Array.Empty<string>();
var _iter = 0;
string String()
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Split(' '), 0);
    return _input[_iter++];
}
T I<T>() where T : IParsable<T> => T.Parse(String(), null);
#endregion

var n = I<long>();
var m = I<long>();
if (n % 2 == 0) Console.WriteLine(n * m);
else
{
    var bits = new List<int>();
    for (var i = 0; i < 31; i++)
    {
        var d = 1 << i;
        if ((m & d) > 0) bits.Add(i);
    }
    var ans = (n - 1) * m;
    if (bits.Count >= 2)
    {
        bits.Reverse();
        for (var i = bits[0] - 1; i >= 0; i--)
        {
            var d = 1 << i;
            if ((m & d) == 0) ans += d * 2;
        }
    }
    Console.WriteLine(ans);
}