#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
const int MAXN = 3e5+2;
signed main() {
cin.tie(nullptr); cout.tie(nullptr);
ios_base::sync_with_stdio(false);
int n;
cin >> n;
map<int, stack<int>> m;
int undone_index[n+1];
undone_index[0] = 0;
int state[n+1];
state[0] = 0;
m[0].push(0);
int op_level[n+1];
for (int i = 1; i <= n; i++) {
int op;
cin >> op;
if (op > 0) {
// edit op
m[0].push(i);
state[i] = op;
op_level[i] = 0;
} else {
// undo op
op = -op;
op_level[i] = op;
auto itr = m.lower_bound(op);
itr--;
m[op].push(i);
undone_index[i] = itr->second.top();
itr->second.pop();
if (op_level[undone_index[i]] != 0) {
m[op_level[undone_index[i]]].push(undone_index[undone_index[i]]);
}
if (itr->second.size() == 0) {
m.erase(itr);
itr = m.lower_bound(op);
itr--;
}
state[i] = state[itr->second.top()];
}
cout << state[i] << endl;
}
cout.flush();
return 0;
}
