#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
vector<int> BIT;
int n, q;
int getSum(int index) {
  int sum = 0;
  while (index > 0) {
    sum += BIT[index];
    index -= index & (-index);
  }
  return sum;
}
void update(int index, int val) {
  while (index <= n) {
    BIT[index] += val;
    index += index & (-index);
  }
}
void solve() {
  cin >> n >> q;
  BIT = vector<int>(n + 1, 0);
  vector<int> arr(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> arr[i];
    update(arr[i], 1);
  }
  int k;
  while (q--) {
    cin >> k;
    if (k > 0) {
      update(k, 1);
    } else {
      k = -k;
      int l = 1, r = n;
      int ans = 0;
      while (l <= r) {
        int mid = l + (r - l) / 2;
        int sum = getSum(mid);
        if (sum < k) {
          l = mid + 1;
        } else {
          ans = mid;
          r = mid - 1;
        }
      }
      update(ans, -1);
    }
  }
  int l = 1, r = n;
  int ans = 0;
  while (l <= r) {
    int mid = l + (r - l) / 2;
    int sum = getSum(mid);
    int sum2 = getSum(mid - 1);
    if (sum <= 0) {
      l = mid + 1;
    } else if (sum > 0 && sum == sum2) {
      r = mid - 1;
    } else {
      ans = mid;
      break;
    }
  }
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
}
