class Set(): #BinaryIndexedTree
    def __init__(self, valuelist, INF=10**18+1):
        self.n = len(valuelist) + 1
        self.value = sorted(valuelist) + [INF]
        self.comp = {v : k for k, v in enumerate(self.value, 1)}
        self.bit = BinaryIndexedTree(self.n)

    def insert(self, x, k=1):
        self.bit.add(self.comp[x], k)

    def delete(self, x, k=1):
        self.bit.add(self.comp[x], -k)

    def count(self, x):
        return self.bit.get(self.comp[x])

    def sum(self, x):
        return self.bit.sum(self.comp[x])

    def get(self, k): #k個以下のときはINFを返す
        return self.value[self.bit.bisect_left(k) - 1]

class BinaryIndexedTree(): #1-indexed
    def __init__(self, n):
        self.n = n
        self.tree = [0 for _ in range(n + 1)]

    def sum(self, idx):
        res = 0
        while idx:
            res += self.tree[idx]
            idx -= idx & -idx
        return res

    def get(self, idx):
        return self.sum(idx) - self.sum(idx - 1)

    def add(self, idx, x):
        while idx <= self.n:
            self.tree[idx] += x
            idx += idx & -idx

    def bisect_left(self, x):
        if x <= 0: return 0
        res, tmp = 0, 2**((self.n).bit_length() - 1)
        while tmp:
            if res + tmp <= self.n and self.tree[res + tmp] < x:
                x -= self.tree[res + tmp]
                res += tmp
            tmp >>= 1
        if res >= self.n:
            return self.n
        return res + 1

INF = 10**18 + 1

N, K = map(int, input().split())

S = Set(range(1000001))

for _ in range(N):
    w = int(input())
    if w > 0:
        if S.sum(INF) - S.sum(w) + S.count(w) < K:
            S.insert(w)
    else:
        if S.count(-w) > 0:
            S.delete(-w)

print(S.sum(INF))