/* -*- coding: utf-8 -*-
 *
 * 2370.cc:  No.2370 He ate many cakes - yukicoder
 */

#include<cstdio>
#include<queue>
#include<algorithm>
#include<utility>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 30;
const int MAX_M = MAX_N / 2;
const int MBITS = 1 << MAX_M;

/* typedef */

using ll = long long;
using pli = pair<ll,int>;

/* global variables */

int as[MAX_N];
ll s0[MBITS], s1[MBITS];

/* subroutines */

/* main */

int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  for (int i = 0; i < n; i++) scanf("%d", as + i);

  int m0 = (n + 1) / 2, m1 = n - m0;
  int mbits0 = 1 << m0, mbits1 = 1 << m1;

  s0[0] = 0;
  for (int bits = 1, msb = 1, msi = 0; bits < mbits0; bits++) {
    if ((msb << 1) <= bits) msb <<= 1, msi++;
    s0[bits] = s0[bits ^ msb] + as[msi];
  }
  sort(s0, s0 + mbits0, greater<ll>());

  s1[0] = 0;
  for (int bits = 1, msb = 1, msi = 0; bits < mbits1; bits++) {
    if ((msb << 1) <= bits) msb <<= 1, msi++;
    s1[bits] = s1[bits ^ msb] + as[m0 + msi];
  }
  sort(s1, s1 + mbits1, greater<ll>());

  priority_queue<pli> q;
  for (int i = 0; i < mbits0; i++)
    q.push({s0[i] + s1[0], 0});

  int c = 0;
  ll sk = 0;
  while (c < k) {
    auto [s, u] = q.top(); q.pop();
    if (++c >= k) { sk = s; break; }

    if (u + 1 < mbits1)
      q.push({s - s1[u] + s1[u + 1], u + 1});
  }

  printf("%lld\n", sk);
  
  return 0;
}