#include <bits/stdc++.h>
using namespace std;
long long int mod = 1000000007;
long long int maxn = 200001;
long long int binpow(long long int a, long long int b, long long int mod) {
  long long int res = 1;
  while (b > 0) {
    if (b % 2) {
      res = (res * a) % mod;
      b--;
    }
    a = (a * a) % mod;
    b /= 2;
  }
  return res % mod;
}
long long int binpow(long long int a, long long int b) {
  long long int res = 1;
  while (b > 0) {
    if (b % 2) {
      res = (res * a);
      b--;
    }
    a = (a * a);
    b /= 2;
  }
  return res;
}
bool isPrime(long long int n) {
  if (n == 1) return false;
  for (long long int i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
struct FenwickTree {
  vector<long long int> tree;
  long long int n;
  void init(long long int n) {
    this->n = n + 1;
    tree.assign(n + 1, 0);
  }
  long long int sum(long long int idx) {
    long long int ret = 0;
    for (; idx > 0; idx -= idx & -idx) ret += tree[idx];
    return ret;
  }
  long long int sum(long long int l, long long int r) {
    return sum(r) - sum(l - 1);
  }
  void add(long long int idx, long long int delta) {
    for (; idx <= n; idx += idx & -idx) tree[idx] += delta;
  }
};
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int n, q;
  cin >> n >> q;
  FenwickTree bit;
  bit.init(n);
  for (long long int i = 0; i < n; ++i) {
    long long int x;
    cin >> x;
    bit.add(x, 1);
  }
  while (q--) {
    long long int k;
    cin >> k;
    if (k >= 1) {
      bit.add(k, 1);
    } else {
      k = -k;
      long long int beg = 1, end = n;
      long long int ans;
      while (beg <= end) {
        long long int mid = (beg + end) / 2;
        long long int cur_pref = bit.sum(mid);
        if (cur_pref >= k)
          ans = mid, end = mid - 1;
        else
          beg = mid + 1;
      }
      bit.add(ans, -1);
    }
  }
  long long int ans = 0;
  for (long long int i = 1; i <= n; ++i)
    if (bit.sum(i)) {
      ans = i;
      break;
    }
  cout << ans << '\n';
  return 0;
}
