#include <bits/stdc++.h>
using namespace std;
template <typename Tp>
inline void outarr(Tp _begin, Tp _end, const char* _delim = " ") {
  for (Tp current = _begin; current != _end; ++current) {
    std::cout << *current << _delim;
  }
  std::cout << '\n';
}
using ll = long long;
using pii = std::pair<int, int>;
constexpr int INF = 0x3f3f3f3f;
constexpr int MOD = static_cast<const int>(1e9 + 7);
int tree[1000000];
void Update(int i, int x, int n) {
  for (; i < n; i |= i + 1) {
    tree[i] += x;
  }
}
int Sum(int r) {
  int res = 0;
  for (; r >= 0; r = (r & (r + 1)) - 1) {
    res += tree[r];
  }
  return res;
}
int Sum(int l, int r) { return Sum(r) - Sum(l - 1); }
int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr);
  int n, q;
  cin >> n >> q;
  for (int i = 0; i < (n); ++i) {
    int x;
    cin >> x;
    Update(x - 1, 1, n);
  }
  while (q--) {
    int k;
    cin >> k;
    if (k > 0) {
      Update(k - 1, 1, n);
    } else {
      k = -k;
      int l = 0;
      int r = n - 1;
      while (l <= r) {
        int mid = (l + r) >> 1;
        if (Sum(0, mid) < k) {
          l = mid + 1;
        } else {
          r = mid - 1;
        }
      }
      Update(l, -1, n);
    }
  }
  if (Sum(0, n - 1) == 0) {
    return cout << (0) << '\n', 0;
    ;
  }
  int l = 0;
  int r = n - 1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (Sum(0, mid) < 1) {
      l = mid + 1;
    } else {
      r = mid - 1;
    }
  }
  cout << l + 1 << "\n";
  return 0;
}
