#include <bits/stdc++.h>
using namespace std;
vector<int> fenwick(1000002);
vector<int> cnt(1000002);
int n, q;
void update(int pos, int del) {
  while (pos <= n) {
    fenwick[pos] += del;
    pos += pos & (-pos);
  }
}
int query(int pos) {
  int s = 0;
  while (pos) {
    s += fenwick[pos];
    pos -= pos & (-pos);
  }
  return s;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(nullptr);
  scanf("%d%d", &n, &q);
  for (int i = 1; i <= n; i++) {
    int ai;
    scanf("%d", &ai);
    update(ai, 1);
    cnt[ai]++;
  }
  while (q--) {
    int k;
    scanf("%d", &k);
    if (k < 0) {
      int lo = 0, hi = n;
      while (lo + 1 != hi) {
        int mid = (lo + hi) / 2;
        if (query(mid) >= k * -1)
          hi = mid;
        else
          lo = mid;
      }
      update(hi, -1);
      cnt[hi]--;
    } else {
      update(k, 1);
      cnt[k]++;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (cnt[i]) {
      printf("%d\n", i);
      return 0;
    }
  }
  cout << 0 << '\n';
  return 0;
}
