#include <bits/stdc++.h>
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
typedef long long ll;
typedef pair<int, int> pii;
const int maxn = 300010;
struct PersTree {
// simple persistent segment tree
// the find query is a bit simpler than normal
struct Node {
Node *l, *r;
int minval;
Node() : l(nullptr), r(nullptr), minval(maxn) {}
Node(int val) : l(nullptr), r(nullptr), minval(val) {}
Node(Node *l, Node *r) : l(l), r(r), minval(maxn) {
if (l) minval = min(minval, l->minval);
if (r) minval = min(minval, r->minval);
}
};
vector<Node*> roots;
Node* build(int tl, int tr) {
if (tl == tr) return new Node();
int tm = (tl + tr) / 2;
return new Node(build(tl, tm), build(tm+1, tr));
}
Node* update(Node* v, int tl, int tr, int pos, int val) {
if (tl == tr) return new Node(val);
int tm = (tl + tr) / 2;
if (pos <= tm) {
return new Node(update(v->l, tl, tm, pos, val), v->r);
} else {
return new Node(v->l, update(v->r, tm+1, tr, pos, val));
}
}
// find max. pos with val < wanted val
// like doing prev(lower_bound) on an array
int find(Node* v, int tl, int tr, int val) {
if (tl == tr) return tl;
int tm = (tl + tr) / 2;
if (v->r->minval < val) {
return find(v->r, tm+1, tr, val);
} else {
return find(v->l, tl, tm, val);
}
}
} tree;
int n;
int ans[maxn];
int main() {
ios::sync_with_stdio(false); cin.tie(0);
cin >> n;
ans[0] = 0;
tree.roots.push_back(tree.build(1, n));
for (int i = 1; i <= n; ++i) {
int a;
cin >> a;
if (a > 0) {
// state now = the state right before
// (but also add this action)
ans[i] = a;
tree.roots.push_back(tree.update(tree.roots[i-1], 1, n, i, 0));
} else {
a = -a;
// state now = the state BEFORE the action we are undoing
// (but also add this action)
int j = tree.find(tree.roots[i-1], 1, n, a) - 1;
ans[i] = ans[j];
tree.roots.push_back(tree.update(tree.roots[j], 1, n, i, a));
}
cout << ans[i] << '\n';
}
}
