#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5, L = 19;
int n, q;
int ar[N], psum[N];
void add(int x) {
  ar[x]++;
  for (int i = x; i <= n; i += i & -i) psum[i]++;
}
void del(int x) {
  ar[x]--;
  for (int i = x; i <= n; i += i & -i) psum[i]--;
}
int binser(int x) {
  int r = 0, a = 0;
  for (int i = L; i >= 0; i--) {
    r += 1 << i;
    if (r > n || a + psum[r] >= x)
      r -= 1 << i;
    else
      a += psum[r];
  }
  return r + 1;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> q;
  for (int i = 1; i <= n; i++) {
    int x;
    cin >> x;
    add(x);
  }
  while (q--) {
    int x;
    cin >> x;
    if (x < 0) {
      x = abs(x);
      int pos = binser(x);
      del(pos);
    } else
      add(x);
  }
  for (int i = 1; i <= n; i++) {
    if (ar[i] == 0) continue;
    cout << i << '\n';
    return 0;
  }
  cout << "0\n";
  return 0;
}
