#include <bits/stdc++.h>
char *fs, *ft, buf[1 << 20];
inline int read() {
  int x = 0, f = 1;
  char ch =
      (fs == ft && (ft = (fs = buf) + fread(buf, 1, 1 << 20, stdin), fs == ft))
          ? 0
          : *fs++;
  ;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = (fs == ft &&
          (ft = (fs = buf) + fread(buf, 1, 1 << 20, stdin), fs == ft))
             ? 0
             : *fs++;
    ;
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = (fs == ft &&
          (ft = (fs = buf) + fread(buf, 1, 1 << 20, stdin), fs == ft))
             ? 0
             : *fs++;
    ;
  }
  return x * f;
}
using namespace std;
const int N = 1e6 + 5;
const int inf = 0x7fffffff;
const int mod = 998244353;
const double eps = 1e-6;
const double PI = acos(-1);
int sum[N << 2];
void in(int p, int l, int r, int k) {
  if (l == r) {
    sum[p]++;
    return;
  }
  int mid = l + r >> 1;
  if (k <= mid)
    in(p << 1, l, mid, k);
  else
    in(p << 1 | 1, mid + 1, r, k);
  sum[p] = sum[p << 1] + sum[p << 1 | 1];
}
void del(int p, int l, int r, int k) {
  if (l == r) {
    sum[p]--;
    return;
  }
  int mid = l + r >> 1;
  if (sum[p << 1] >= k)
    del(p << 1, l, mid, k);
  else
    del(p << 1 | 1, mid + 1, r, k - sum[p << 1]);
  sum[p] = sum[p << 1] + sum[p << 1 | 1];
}
int ask(int p, int l, int r) {
  if (l == r) {
    return l;
  }
  int mid = l + r >> 1;
  if (sum[p << 1] != 0) return ask(p << 1, l, mid);
  if (sum[p << 1 | 1] != 0) return ask(p << 1 | 1, mid + 1, r);
}
signed main() {
  int n = read(), q = read();
  for (int i = 1; i <= n; i++) {
    int x = read();
    in(1, 1, n, x);
  }
  while (q--) {
    int x = read();
    if (x > 0)
      in(1, 1, n, x);
    else {
      x = -x;
      del(1, 1, n, x);
    }
  }
  if (sum[1] != 0) {
    cout << ask(1, 1, n) << '\n';
  } else
    cout << 0 << '\n';
}
