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<Long, Integer> evCount = new TreeMap<>();
        TreeMap<Long, Integer> odCount = new TreeMap<>();
        evCount.put(0L, 1);
        odCount.put(0L, 1);
        for (int i = 0; i < n; i++) {
            int x = sc.nextInt();
            TreeMap<Long, Integer> 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();
    }
    
}