#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
int n, q;
int bit[maxn];
void add(int x, int v = 1) {
  while (x < maxn) {
    bit[x] += v;
    x += x & -x;
  }
}
int sum(int x) {
  int ret = 0;
  while (x > 0) {
    ret += bit[x];
    x -= x & -x;
  }
  return ret;
}
void del(int k) {
  int l = 0, r = n;
  while (l + 1 < r) {
    int mid = (l + r) >> 1;
    if (sum(mid) >= k)
      r = mid;
    else
      l = mid;
  }
  add(r, -1);
}
int main() {
  scanf("%d%d", &n, &q);
  for (int i = 0; i < n; i++) {
    int x;
    scanf("%d", &x);
    add(x);
  }
  while (q--) {
    int x;
    scanf("%d", &x);
    if (x > 0)
      add(x);
    else {
      del(-x);
    }
  }
  if (sum(maxn - 1) == 0)
    printf("0\n");
  else {
    int l = 0, r = n;
    while (l + 1 < r) {
      int mid = (l + r) >> 1;
      if (sum(mid) >= 1)
        r = mid;
      else
        l = mid;
    }
    printf("%d\n", r);
  }
  return 0;
  return 0;
}
