#![allow(non_snake_case)]
#![allow(dead_code)]
#![allow(unused_macros)]
#![allow(unused_imports)]

use std::str::FromStr;
use std::io::*;
use std::collections::*;
use std::cmp::*;

struct Scanner<I: Iterator<Item = char>> {
    iter: std::iter::Peekable<I>,
}

macro_rules! exit {
    () => {{
        exit!(0)
    }};
    ($code:expr) => {{
        if cfg!(local) {
            writeln!(std::io::stderr(), "===== Terminated =====")
                .expect("failed printing to stderr");
        }
        std::process::exit($code);
    }}
}

impl<I: Iterator<Item = char>> Scanner<I> {
    pub fn new(iter: I) -> Scanner<I> {
        Scanner {
            iter: iter.peekable(),
        }
    }

    pub fn safe_get_token(&mut self) -> Option<String> {
        let token = self.iter
            .by_ref()
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>();
        if token.is_empty() {
            None
        } else {
            Some(token)
        }
    }

    pub fn token(&mut self) -> String {
        self.safe_get_token().unwrap_or_else(|| exit!())
    }

    pub fn get<T: FromStr>(&mut self) -> T {
        self.token().parse::<T>().unwrap_or_else(|_| exit!())
    }

    pub fn vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
        (0..len).map(|_| self.get()).collect()
    }

    pub fn mat<T: FromStr>(&mut self, row: usize, col: usize) -> Vec<Vec<T>> {
        (0..row).map(|_| self.vec(col)).collect()
    }

    pub fn char(&mut self) -> char {
        self.iter.next().unwrap_or_else(|| exit!())
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.get::<String>().chars().collect()
    }

    pub fn line(&mut self) -> String {
        if self.peek().is_some() {
            self.iter
                .by_ref()
                .take_while(|&c| !(c == '\n' || c == '\r'))
                .collect::<String>()
        } else {
            exit!();
        }
    }

    pub fn peek(&mut self) -> Option<&char> {
        self.iter.peek()
    }
}

trait Joinable {
    fn join(self, sep: &str) -> String;
}

impl<U: ToString, T: Iterator<Item = U>> Joinable for T {
    fn join(self, sep: &str) -> String {
        self.map(|x| x.to_string()).collect::<Vec<_>>().join(sep)
    }
}

struct Solver {
    K: usize,
    ones: Vec<usize>,
    zeros: Vec<usize>,
}

impl Solver {
    fn dfs(&mut self, i: usize, smaller: usize) -> usize {
        if smaller == 1 {
            let mut ans = 0;
            let mut j = i;
            while j != 0 {
                ans += (1<<j) * max(self.ones[j], self.zeros[j]);
                j -= 1;
            }
            ans += (1<<j) * max(self.ones[j], self.zeros[j]);
            return ans;
        }
        let bit = self.K & 1<<i;
        if i == 0 {
            return if bit == 0 { self.ones[0] } else { self.zeros[0] }
        }
        if bit == 0 {
            self.dfs(i-1, 0) + (1<<i) * self.ones[i]
        } else {
            max(
                self.dfs(i-1, 0) + (1<<i)*(if bit == 0 { self.ones[i] } else { self.zeros[i] }),
                self.dfs(i-1, 1) + (1<<i) * self.ones[i])
        }
    }
}

fn main() {
    let cin = stdin();
    let cin = cin.lock();
    let mut sc = Scanner::new(cin.bytes().map(|c| c.unwrap() as char));
    let N: usize = sc.get();
    let K: usize = sc.get();
    let A: Vec<usize> = sc.vec(N);
    let mut ones = vec![0; 51];
    let mut zeros = vec![0; 51];
    for i in (0..51).rev() {
        for j in 0..N {
            if A[j] & 1<<i != 0 {
                ones[i] += 1;
            } else {
                zeros[i] += 1;
            }
        }
    }
    let mut s = Solver { K: K, ones: ones, zeros: zeros };
    let ans = s.dfs(50, 0);
    println!("{}", ans);
}


Measured memory_bytes: 4352