import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container, std.format;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] lreads(T = long)(long n){return generate(()=>readln.chomp.to!T()).take(n).array();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long N;
    ulong K;
    scan(N, K);
    auto A = aryread!ulong();
    auto cnt = new long[](64);
    foreach (i; 0 .. 64)
    {
        foreach (a; A)
        {
            cnt[i] += (a & (1 << i)) != 0;
        }
    }
    ulong ans = A.sum();
    foreach (i; 0 .. 64)
        if ((K & (1UL << i)) != 0)
        {
            ulong x;
            foreach (j; 0 .. i + 1)
                x |= ((cnt[j] < N / 2) ? 1UL : 0UL) << i;
            foreach (j; i + 1 .. 64)
                x |= K & (1UL << j);
            ulong tmp;
            foreach (a; A)
                tmp += x ^ a;
            // writefln("%s, %064b, %s", i, x, tmp);
            ans = max(ans, tmp);
        }
    writeln(ans);
}
