#include <bits/stdc++.h>
using namespace std;
long long MOD = 1e9 + 7, MAX = 1e18;
vector<long long> Bit;
long long n, q;
long long query(long long x) {
  long long sum = 0;
  while (x) {
    sum += Bit[x];
    x -= (x & -x);
  }
  return sum;
}
void upd(long long x, long long v) {
  while (x <= n) {
    Bit[x] += v;
    x += (x & -x);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long i = 0, a, l, r, m;
  cin >> n >> q;
  Bit.resize(n + 10);
  while (i < n) cin >> a, upd(a, 1), i++;
  while (q--) {
    cin >> a;
    if (a > 0)
      upd(a, 1);
    else {
      a *= -1;
      l = 1, r = n;
      while (l <= r) {
        m = (l + r) / 2;
        if (query(m) >= a)
          i = m, r = m - 1;
        else
          l = m + 1;
      }
      upd(i, -1);
    }
  }
  l = 0, r = n, a = query(n);
  while (l <= r) {
    m = (l + r) / 2;
    if (query(m) >= a)
      i = m, r = m - 1;
    else
      l = m + 1;
  }
  cout << i;
  return 0;
}
