import bisect
import copy
import decimal
import fractions
import heapq
import itertools
import math
import random
import sys
import time
from collections import Counter,deque,defaultdict
from functools import lru_cache,reduce
from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max
def _heappush_max(heap,item):
    heap.append(item)
    heapq._siftdown_max(heap, 0, len(heap)-1)
def _heappushpop_max(heap, item):
    if heap and item < heap[0]:
        item, heap[0] = heap[0], item
        heapq._siftup_max(heap, 0)
    return item
from math import gcd as GCD
read=sys.stdin.read
readline=sys.stdin.readline
readlines=sys.stdin.readlines
write=sys.stdout.write
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
#sys.set_int_max_str_digits(10**9)

def Bisect_Int(ok,ng,is_ok):
    while abs(ok-ng)>1:
        mid=(ok+ng)//2
        if is_ok(mid):
            ok=mid
        else:
            ng=mid
    return ok

N,K=map(int,readline().split())
A=list(map(int,readline().split()))
K=2**N+1-K
n=N//2
lst0=[]
for bit in range(1<<n):
    lst0.append(sum(A[i] for i in range(n) if bit&1<<i))
lst0.sort()
lst1=[]
for bit in range(1<<N-n):
    lst1.append(sum(A[i] for i in range(n,N) if bit&1<<i-n))
def is_ok(ans):
    cnt=0
    for s in lst1:
        cnt+=bisect.bisect_right(lst0,ans-1-s)
    return cnt<K
inf=1<<60
ans=Bisect_Int(-inf,inf,is_ok)
print(ans)