#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, q, chk[1000001], bu[1000001], sq = 1000;
int main() {
  scanf("%d %d", &n, &q);
  for (int i = 1; i <= n; i++) {
    int a;
    scanf("%d", &a);
    chk[a]++;
    bu[a / sq]++;
  }
  for (int i = 1; i <= q; i++) {
    int a;
    scanf("%d", &a);
    if (a > 0) {
      chk[a]++;
      bu[a / sq]++;
    } else {
      a = -a;
      for (int j = 0; j <= n / sq; j++) {
        if (bu[j] >= a) {
          for (int k = 0; k < sq; k++) {
            if (chk[j * sq + k] >= a) {
              chk[j * sq + k]--;
              break;
            }
            a -= chk[j * sq + k];
          }
          bu[j]--;
          break;
        }
        a -= bu[j];
      }
    }
  }
  for (int i = 1; i <= n; i++)
    if (chk[i]) return !printf("%d", i);
  printf("0");
}
