#include <bits/stdc++.h>
using namespace std;
#define SC               scanf
#define PF               printf
#define ull              unsigned long long
#define ld               long double
#define F                first
#define S                second
#define pb               push_back
#define sort_a(a)        sort(a.begin(),a.end());
#define sort_d(a)        sort(a.rbegin(),a.rend());
#define READ(f)          freopen(f, "r", stdin)
#define WRITE(f)         freopen(f, "w", stdout)
#define rev(s)           reverse(s.begin(),s.end())
#define P(ok)            cout << (ok ? "YES\n": "NO\n")
#define __Heart__              ios_base :: sync_with_stdio(false); cin.tie(NULL);
#define ll long long
typedef pair< ll , ll>                   PII;
void solve()
{
   ll n , k ; cin >> n >> k ; ll a[n] ;
    map < int , int > bit ;
   for(int i = 0 ; i < n ; i++)
   {
      cin >> a[i] ;
      for(int j = 0 ; j < 50 ; j++)
      {
         if((1LL << j) & a[i]) bit[j]++ ;
      }
   }
   ll x = 0 , Ans = 0;
   for(ll i = 50 ; i >= 0 ; i--)
   {
       ll zero = n - bit[i] ;
       ll add = x + (1LL << i) ;
      // cout << zero << " " << bit[i] << " " << k << " " << add << endl ;
       if(zero >= bit[i] && add <= k) x = add ;

   }
  // cout << x << endl ;
   for(int i = 0 ; i < n ; i++) Ans += (a[i] ^ x) ;

   cout << Ans << "\n" ;

}
int main()
{
     __Heart__
     //READ("0out.txt") ;
     int t ; t = 1 ; while(t--) solve() ;
}