#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> p) {
  os << '(' << p.first << ',' << p.second << ')';
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> p) {
  os << "{ ";
  for (auto i : p) {
    os << i << ",";
  }
  os << "\b";
  os << "}";
  return os;
}
template <typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &p) {
  in >> p.first >> p.second;
  return in;
}
template <typename T>
void keySort(vector<T> &arr, vector<int> &key) {
  int n = arr.size();
  if (key.size() != n) {
    throw runtime_error("Size of data array not equals to size of key array");
  }
  vector<T> ans(n);
  int ar[n];
  for (int i = 0; i < n; i++) {
    ar[key[i]] = i;
  }
  for (int i = 0; i < n; i++) {
    ans[i] = arr[ar[i]];
  }
  arr = ans;
}
class fenwikTree {
  vector<int> BIT;
  int n;
  int sum(int i) {
    int ans = 0;
    while (i > 0) {
      ans += BIT[i];
      i = i - ((i) & -(i));
    }
    return ans;
  }

 public:
  fenwikTree(int n) {
    this->n = n + 1;
    BIT.resize(n + 1, 0);
  }
  void update(int i, int val) {
    while (i > 0 && i < n) {
      BIT[i] += val;
      i = i + ((i) & -(i));
    }
  }
  int kthSmallest(int k) {
    int l = 0;
    int h = n;
    while (l < h) {
      int m = (l + h) >> 1;
      if (k <= sum(m)) {
        h = m;
      } else {
        l = m + 1;
      }
    }
    return l;
  }
  void insert(int x) { update(x, 1); }
  void removeAtRank(int x) {
    int v = kthSmallest(x);
    update(v, -1);
  }
  int findRank(int x) { return sum(x); }
};
void solve();
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  solve();
  return 0;
}
void solve() {
  int n, q;
  cin >> n >> q;
  fenwikTree tree(n);
  int tmp;
  for (int i = 0; i < n; i++) {
    cin >> tmp;
    tree.insert(tmp);
  }
  while (q--) {
    cin >> tmp;
    if (tmp < 0) {
      tree.removeAtRank((-tmp));
    } else {
      tree.update(tmp, 1);
    }
  }
  int ans = tree.kthSmallest(1);
  if (ans > n) {
    ans = 0;
  }
  cout << ans << endl;
}
