#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <cmath>
#include <queue>
#pragma GCC optimize("O3")
 const long long mod1=998244353;
    const long long mod2=1000000007;
long long pow(int a,int b) {
    if (b==0 || a==1) return 1;

    if (b%2==0) { long long k=pow(a,b/2); return (k*k); }
    else { long long k=pow(a,b/2); return k*k*a; }
}
long long powmod(long long a,long long b,long long mod) {
    if (b==0 || a==1)  {if (mod==1) return 0; else return 1; }

    if (b%2==0) { long long k=powmod(a,b/2,mod); return (k*k)%mod; }
    else {long long k=powmod(a,b/2,mod); return ( (k*k) %mod *a)% mod; }
}
long long gcd(long long a, long long b) {
    if (a==0) return b;
    if (b==0) return a;
    if (a>b) return gcd(a%b,b); else return gcd(b%a,a);
}
int prime(int p) { // 1 - простое
    for (int i=2;i*i<=p;i++) {
        if (p%i==0 && i<p) return 0;
    }
    return 1;
}
long long sqr(long long i) {
    return i*i;
}
using namespace std;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

     /* --------- */

 int a;
 cin>>a;
 vector <int> ans;
 vector <pair<int,pair<int,int>>> cur;
 int ser11=-1,ser21=-1;
 int ser12=0,ser22=0;
 int last1=0;
 int last2=0;
 int first1=0;
 int first2=0;
 int t=0;
 int pushes=0;
 for (int i=0;i<a;i++) {
     char q;
     cin>>q;
     if (q=='-') {  ans.push_back(cur[first2].first);
    // if (i==5) { cout<<t; return 0; }
     if (t==1) {first1=-1; last1=-1; first2=-1; last2=-1; }
     else  {
  //   if (t==2) cout<<first2<<" "<<last1;
 //cout<<first2<<" ";
       first2=cur[first2].second.second;
   //  cout<<first2<<"\n";
     first1=cur[first2].first;
     if (t%2==0) {
         ser11=ser21;
         ser12=ser22;
         ser21=cur[ser21].second.second;
         ser22=cur[ser21].first;
     }
     }

     t--;

     } else {
         if (q=='+') {int w; cin>>w;

         if (t==0) { first1=w; first2=pushes; last1=pushes; last2=w; t++;
         cur.push_back({w, {last1, -1}}); pushes++;} else {
         cur[last1].second.second=pushes;
      //   cout<<last1;
      cur.push_back({w, {last1, -1}});
         last1=pushes;
          last2=w;
          t++;
         if (t==2) {ser11=first2; ser21=last1; ser12=cur[ser11].first; ser22=cur[ser21].first; }
         pushes++;


             if (t%2==1) {ser11=ser21; ser12=ser22;
                 ser21=cur[ser21].second.second;
                 ser22=cur[ser21].first;
             }
         }
         }





         else { int w; cin>>w;

         if (t==0) { cur.push_back({w, {-1, -1}}); first1=w; first2=pushes; last1=pushes; last2=w; pushes++; t++; } else
         if (t==1) {cur.push_back({w, {first2, -1}});  last1=pushes; cur[first2].second.second=last1; ser11=first2; last2=w; ser21=last1; pushes++; t++; } else
         if (t%2==0) {
             cur.push_back({w, {ser11,ser21}});

             cur[ser11].second.second=pushes;

             cur[ser21].second.first=pushes;
             ser11=pushes;
             ser12=w; pushes++; t++;
         } else {
             cur.push_back({w, {ser11,ser21}});
             cur[ser11].second.second=pushes;
             cur[ser21].second.first=pushes;
             ser21=pushes;
             ser22=w;
             pushes++;
             t++;
         }

         }
     }

     //if (i==2) {cout<<first2<<" "<<last1<<"\n"; }
    // if (i==4) return 0;
//if (i==6) return 0;
 }

 for (int i=0;i<ans.size();i++) cout<<ans[i]<<"\n";
   /* --------- */
    return 0;
}