#include <bits/stdc++.h>
using namespace std;
const long long mod = 998244353;
const long long N = 1e6 + 1;
long long n;
long long bit[N];
long long resp(long long x) { return (x & (-x)); }
void update(long long idx, long long val) {
  while (idx <= n) {
    bit[idx] += val;
    idx += resp(idx);
  }
}
long long sum(long long idx) {
  long long res = 0;
  while (idx > 0) {
    res += bit[idx];
    idx -= resp(idx);
  }
  return res;
}
void solve() {
  long long q;
  cin >> n >> q;
  long long mxn = log2(n);
  for (long long i = 0; i < n; i++) {
    long long x;
    cin >> x;
    update(x, 1);
  }
  while (q--) {
    long long k;
    cin >> k;
    if (k > 0)
      update(k, 1);
    else {
      k *= -1;
      long long ans = 0;
      long long s = 0;
      for (long long i = mxn; i >= 0; i--) {
        if (ans + (1 << i) <= n && s + bit[ans + (1 << i)] < k) {
          ans += (1 << i);
          s += bit[ans];
        }
      }
      ans++;
      update(ans, -1);
    }
  }
  long long s = sum(n);
  if (s == 0)
    cout << 0 << "\n";
  else {
    for (long long i = 1; i <= n; i++) {
      if (sum(i) > 0) {
        cout << i << "\n";
        break;
      }
    }
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t = 1;
  while (t--) {
    solve();
  }
}
