#include <bits/stdc++.h>
using namespace std;
long long int n, f[1000007];
void update(long long int i, long long int add) {
  while (i > 0 && i <= 1000007) {
    f[i] += add;
    i += (i & (-i));
  }
}
long long int sum(long long int i) {
  long long int s = 0;
  while (i > 0) {
    s += f[i];
    i = i - (i & (-i));
  }
  return s;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int q, i, N = 1000007;
  cin >> n >> q;
  for (i = 0; i < n; i++) {
    long long int num;
    cin >> num;
    update(num, 1);
  }
  while (q--) {
    long long int x;
    cin >> x;
    if (x > 0) {
      update(x, 1);
    } else {
      x = -1 * x;
      long long int low = 0, high = N;
      while (low < high) {
        long long int mid = (low + high) / 2;
        long long int val = sum(mid);
        if (x <= val)
          high = mid;
        else
          low = mid + 1;
      }
      update(low, -1);
    }
  }
  long long int ans = sum(n);
  if (!ans)
    cout << "0" << endl;
  else {
    long long int low = 0, high = N;
    while (low < high) {
      long long int mid = (low + high) / 2;
      long long int val = sum(mid);
      if (ans <= val)
        high = mid;
      else
        low = mid + 1;
    }
    cout << low << endl;
  }
}
