#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
#define INF INT_MAX
#define MOD 1000000007
#define all(x) x.begin(), x.end()
struct PersTree {
PersTree *l, *r;
int key, val, max_val;
PersTree(PersTree *_l, PersTree *_r, int _key, int _val, int _max_val) :
l(_l), r(_r), key(_key), val(_val), max_val(_max_val) {}
PersTree *insert(int _key, int _val){
PersTree *_l = l, *_r = r;
int nval = val;
if(_key < key) _l = _l->insert(_key, _val);
else if(_key == key) nval = _val;
else _r = _r->insert(_key, _val);
return new PersTree(_l, _r, key, nval, max({(_l?_l->max_val:0), nval, (_r?_r->max_val:0)}));
}
int query(int _key){
if(_key < key) return l->query(_key);
else if(_key == key) return max((l?l->max_val:0), val);
else return max({(l?l->max_val:0), val, r->query(_key)});
}
};
PersTree *build(int left, int right){
if(left > right) return NULL;
int m = (left+right)/2;
return new PersTree(build(left, m-1), build(m+1, right), m, 0, 0);
}
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
int N; cin >> N;
vector<PersTree*> A(N+1);
A[0] = build(0, N);
vi ans(N+1);
for(int i = 1; i <= N; i++){
int x; cin >> x;
if(x > 0){
// write operation
ans[i] = x;
A[i] = A[i-1]->insert(0, i);
}else{
// undo operation
int prv = A[i-1]->query(-x-1)-1;
ans[i] = ans[prv];
A[i] = A[prv]->insert(-x, i);
}
cout << ans[i] << "\n";
A[1]->query(10);
}
return 0;
}
