#define NguyenDangQuan the_author

#include <bits/stdc++.h>
#define all(x) x.begin(),x.end()
#define mset(x, i) memset(x,i,sizeof(x))
#define elif else if
#define heap priority_queue
#define fi first
#define se second
#define pb push_back
#define ld long double
#define ll long long
#define ull unsigned long long
#define task "codef"
using namespace std;

int typetest;
inline void fastIOfileinput(){
    ios_base:: sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    typetest = 0;
}

struct segment{
    int v;
};

const int N = 1e6;
int n, q;
int v = 0;
segment st[(N << 2) + 2];

void upd(int id, int in, int l, int r){
    if(id < l || id > r) return;
    else if(id == l && id == r ){
        ++st[in].v;
        return;
    }
    upd(id, in * 2, l, (l + r) / 2);
    upd(id, in * 2 + 1, (l + r) / 2 + 1, r);
    st[in].v = st[in << 1].v + st[in << 1 | 1].v;
}

void update(int id, int in, int l, int r){
    if(l == r && st[in].v + v >= id){
        --st[in].v;
        return;
    }
    if(st[in << 1].v + v >= id)
        update(id, in << 1, l, (l + r) / 2);
    else
        v += st[in << 1].v,
        update(id, in << 1 | 1, (l + r) / 2 + 1, r);
    st[in].v = st[in << 1].v + st[in << 1 | 1].v;
}

int que(int id, int l, int r){
    if(l == r && st[id].v != 0){
        return l;
    }
    if(st[id << 1].v > 0)
        return que(id << 1, l, (l + r) / 2);
    return que(id << 1 | 1, (l + r) / 2 + 1, r);
}

void Enter(){
    cin >> n >> q;
    //build(1, 1, n);
    for(int i = 1; i <= n; ++i){
        int v; cin >> v;
        upd(v, 1, 1, n);
    }
    while(q--){
        int vv; cin >> vv;
        if(vv > 0)
            upd(vv, 1, 1, n);
        else{
                v = 0;
            update(abs(vv), 1, 1, n);
        }
    }
}

void solve(){
    if(st[1].v == 0)
        cout << 0;
    else{
        cout << que(1, 1, n);
    }
}

main(){
    fastIOfileinput();
    if(typetest){
        int t;
        cin >> t;
        while(t--){
            Enter();
            solve();
        }
    }
    else{
        Enter();
        solve();
    }
}