#include <bits/stdc++.h>
using namespace std;
long long maxn = 1000000;
long long BIT[1000001];
void update(long long pos, long long val) {
  for (long long i = pos; i <= maxn; i += i & (-i)) {
    BIT[i] += val;
  }
}
long long bitse(long long val, long long n) {
  long long sum = 0;
  long long pos = 0;
  long long logn = log2(maxn);
  for (long long i = logn; i >= 0; i--) {
    if (pos + (1 << i) <= maxn && (sum + BIT[pos + (1 << i)]) < val) {
      sum += BIT[pos + (1 << i)];
      pos += (1 << i);
    }
  }
  return pos + 1;
}
void solve() {
  long long n, q;
  cin >> n >> q;
  vector<long long> cnt(n + 1, 0);
  long long x;
  for (int i = 0; i < n; i++) {
    cin >> x;
    cnt[x]++;
  }
  for (int i = 1; i <= n; i++) {
    update(i, cnt[i]);
  }
  for (int i = 0; i < q; i++) {
    long long ip;
    cin >> ip;
    if (ip > 0) {
      cnt[ip]++;
      update(ip, 1);
    } else {
      ip = abs(ip);
      long long valatp = bitse(ip, n);
      update(valatp, -1);
      cnt[valatp]--;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (cnt[i] > 0) {
      cout << i << endl;
      break;
    }
    if (i == n) {
      cout << "0" << endl;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
}
