#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool uax(T &x, T y) {
  return (y > x) ? x = y, true : false;
}
template <typename T>
inline bool uin(T &x, T y) {
  return (y < x) ? x = y, true : false;
}
string to_string(char c) { return "'" + string(1, c) + "'"; }
string to_string(string s) { return '"' + s + '"'; }
string to_string(const char *s) { return to_string((string)s); }
template <typename A>
string to_string(A);
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ": " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
  bool f = false;
  string r = "{";
  for (auto x : v) {
    if (f) r += ", ";
    r += to_string(x);
    f = true;
  }
  return r += "}";
}
template <typename A>
string to_string(vector<vector<A>> v) {
  string r;
  for (auto x : v) r += "\n" + to_string(x);
  return r;
}
int Nerr;
template <typename A>
string to_string(A *p) {
  return to_string(vector<A>(p, p + Nerr));
}
void err(istream_iterator<string>) { cerr << endl; }
template <typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
  cerr << *it << " =: " << to_string(a) << "; ";
  err(++it, args...);
}
template <typename T>
void kek(T ans) {
  cout << ans << endl;
  exit(0);
}
int const MOD = 1e9 + 7;
long long const INF = 1e18 + 42;
const int N = 1e6 + 42;
int a[N];
int32_t main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, q;
  cin >> n >> q;
  for (int i = 0; i < n; ++i) {
    int x;
    cin >> x;
    while (x < N) a[x]++, x += x & -x;
  }
  int cnt = n;
  while (q--) {
    int x;
    cin >> x;
    if (x > 0) {
      while (x < N) a[x]++, x += x & -x;
      ++cnt;
    } else {
      x = -x;
      int lo = 1, hi = n;
      while (lo < hi) {
        int md = (lo + hi) >> 1;
        int s = 0;
        int k = md;
        while (k > 0) s += a[k], k -= k & -k;
        if (s < x)
          lo = md + 1;
        else
          hi = md;
      }
      while (lo < N) a[lo]--, lo += lo & -lo;
      --cnt;
    }
  }
  if (cnt == 0) kek(0);
  for (int i = 1; i <= n; ++i) {
    int s = 0;
    int k = i;
    while (k > 0) s += a[k], k -= k & -k;
    if (s > 0) kek(i);
  }
}
