#include <bits/stdc++.h>
using namespace std;
template <typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename T>
ostream &operator<<(ostream &os, const multiset<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
void faltu() { cerr << endl; }
template <typename T>
void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i) cerr << a[i] << ' ';
  cerr << endl;
}
template <typename T, typename... hello>
void faltu(T arg, const hello &...rest) {
  cerr << arg << ' ';
  faltu(rest...);
}
const int fx[] = {+1, -1, +0, +0};
const int fy[] = {+0, +0, +1, -1};
long long Set(long long &N, long long pos) { return N = N | (1ll << pos); }
long long Reset(long long &N, long long pos) { return N = N & ~(1ll << pos); }
bool check(long long N, long long pos) { return (bool)(N & (1ll << pos)); }
void INITIALIZE() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
inline long long add(long long a, long long b) {
  return (a + b >= 1000000007) ? (a + b - 1000000007) : (a + b);
}
inline long long sub(long long a, long long b) {
  return (a - b < 0) ? (a - b + 1000000007) : (a - b);
}
inline long long mul(long long a, long long b) {
  return (a * 1ll * b) % 1000000007;
}
void Binary(long long x) {
  for (int i = 31; i >= 0; i--) {
    if ((1 << i) & x)
      cerr << "1";
    else
      cerr << "0";
  }
  cerr << "\n";
}
long long ncr(long long n, long long r) {
  long long ans = 1;
  if (r > n - r) r = n - r;
  for (long long i = 1; i <= r; i++) {
    ans *= (n - i + 1), ans /= i;
  }
  return ans;
}
long long pow(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = (res * a) % 1000000007;
    b >>= 1;
    a = (a * a) % 1000000007;
  }
  return res;
}
const long long mxn = 1e6 + 5;
vector<long long> bit(mxn), cnt(mxn);
long long n, q;
void update(long long pos, long long val) {
  for (; pos <= n; pos += pos & -pos) {
    bit[pos] += val;
  }
}
long long sum(long long pos) {
  long long ans = 0;
  for (; pos; pos -= pos & -pos) ans += bit[pos];
  return ans;
}
void solve() {
  cin >> n >> q;
  for (long long i = 0; i < n; i++) {
    long long x;
    cin >> x;
    update(x, 1);
    cnt[x]++;
  }
  while (q--) {
    long long x;
    cin >> x;
    if (x > 0) {
      cnt[x]++;
      update(x, 1);
    } else {
      x *= -1;
      long long l = 1, r = n;
      while (l < r) {
        long long mid = (l + r) / 2;
        long long koita = sum(mid);
        if (koita >= x) {
          r = mid;
        } else
          l = mid + 1;
      }
      update(l, -1);
      cnt[l]--;
    }
  }
  for (long long i = 1; i <= n; i++) {
    if (cnt[i]) {
      cout << i << endl;
      return;
    }
  }
  cout << 0 << endl;
}
int main() {
  INITIALIZE();
  int t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
