#include <bits/stdc++.h>
using namespace std;
void update(int x, vector<int> &v) {
  while (x > 0 && x < v.size()) {
    v[x] += 1;
    x = x + (x & (-x));
  }
}
void remove(int x, vector<int> &v) {
  while (x > 0 && x < v.size()) {
    v[x] += -1;
    x = x + (x & (-x));
  }
}
int sum(int x, vector<int> &v) {
  int ans = 0;
  while (x > 0) {
    ans += v[x];
    x = x - (x & (-x));
  }
  return ans;
}
int find(int k, vector<int> &v) {
  int s = 0, e = v.size();
  while (s < e) {
    int mid = (s + e) / 2;
    if (k <= sum(mid, v))
      e = mid;
    else
      s = mid + 1;
  }
  return s;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, q;
  cin >> n >> q;
  vector<int> v(n + 3);
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    update(x, v);
  }
  while (q--) {
    int x;
    cin >> x;
    if (x > 0) {
      update(x, v);
    } else {
      x = -1 * x;
      int ele = find(x, v);
      remove(ele, v);
    }
  }
  for (int i = 1; i <= n; i++) {
    if (v[i] > 0) {
      cout << i;
      return 0;
    }
  }
  cout << 0 << "\n";
  return 0;
}
