#include <bits/stdc++.h>
using namespace std;
struct Fenwick {
  vector<long> v;
  long n;

 public:
  Fenwick(long num) {
    n = num;
    v.assign(num + 1, 0);
  }

 public:
  void update(long i) {
    for (; i <= n; i += i & (-i)) v[i]++;
  }

 public:
  void rem(long i) {
    for (; i <= n; i += i & (-i)) v[i]--;
  }

 public:
  long query(long i) {
    long r = 0;
    for (; i > 0; i -= i & (-i)) r += v[i];
    return r;
  }
};
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, q, sz = 0;
  cin >> n >> q;
  Fenwick s(n + 5);
  vector<int> v(n + 5, 0);
  sz = n;
  for (long i = 0; i < n; i++) {
    int a;
    cin >> a;
    s.update(a);
    v[a]++;
  }
  for (long i = 0; i < q; i++) {
    int k;
    cin >> k;
    if (k > 0) {
      s.update(k);
      v[k]++, sz++;
    } else {
      k = abs(k);
      int l = 1, h = n;
      while (h > l) {
        int mid = (l + h) >> 1;
        int ans = s.query(mid);
        if (ans < k) {
          l = mid + 1;
        } else
          h = mid;
      }
      sz--, v[h]--, s.rem(h);
    }
  }
  if (sz) {
    for (long i = 1; i <= n; i++) {
      if (v[i]) {
        cout << i;
        break;
      }
    }
  } else
    cout << 0;
}
