import java.io.*; import java.util.*; import java.util.stream.*; public class Main { public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); int n = sc.nextInt(); int k = sc.nextInt(); TreeMap evCount = new TreeMap<>(); TreeMap odCount = new TreeMap<>(); evCount.put(0L, 1); odCount.put(0L, 1); for (int i = 0; i < n; i++) { int x = sc.nextInt(); TreeMap counts; if (i % 2 == 0) { counts = evCount; } else { counts = odCount; } if (x == 0) { for (long y : counts.keySet()) { counts.put(y, counts.get(y) * 2); } } else if (x > 0) { Long key = Long.MAX_VALUE; while ((key = counts.lowerKey(key)) != null) { counts.put(key + x, counts.getOrDefault(key + x, 0) + 1); } } else { Long key = Long.MIN_VALUE; while ((key = counts.higherKey(key)) != null) { counts.put(key + x, counts.getOrDefault(key + x, 0) + 1); } } } odCount.put(Long.MAX_VALUE, 0); int sum = 0; Long key = Long.MAX_VALUE; while ((key = odCount.lowerKey(key)) != null) { sum += odCount.get(key); odCount.put(key, sum); } long left = Long.MIN_VALUE / 3; long right = Long.MAX_VALUE / 3; while (right - left > 1) { long m = (left + right) / 2; int current = 0; for (long x : evCount.keySet()) { current += evCount.get(x) * odCount.ceilingEntry(m - x).getValue(); if (current > k) { break; } } if (current >= k) { left = m; } else { right = m; } } System.out.println(left); } } class Utilities { static String arrayToLineString(Object[] arr) { return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n")); } static String arrayToLineString(int[] arr) { return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new)); } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); StringBuilder sb = new StringBuilder(); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public int[] nextIntArray() throws Exception { return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray(); } public String next() throws Exception { while (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }