#include<iostream>
#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
#include<queue>
#include<vector>
#include<string>
#include<map>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
const int maxn = 1e4 + 7;
int n;
multiset<int> up, lo;
stack<int> sta;
void adapt() {int cnt = up.size() + lo.size();int upsz = ceil(cnt / 2.0);while (up.size() < upsz) {up.insert(*lo.begin());lo.erase(lo.begin());}while (up.size() > upsz) {int x = *up.rbegin();lo.insert(x);up.erase(up.find(x));}
}
void push(int x) {up.insert(x);adapt();
}
int peek() {return *(up.rbegin());
}
void pop(int x) {if (up.find(x) != up.end())up.erase(up.find(x));elselo.erase(lo.find(x));adapt();
}
int main() {freopen("in.txt", "r", stdin);cin >> n;while (sta.empty() == false)sta.pop();up.clear(), lo.clear();char cmd[13];int x;while (n--) {cin >> cmd;if (cmd[1] != 'u') {if (lo.empty() && up.empty()) {puts("Invalid");continue;}if (cmd[1] == 'o') {int x = sta.top();sta.pop();cout << x << endl;pop(x);} else if (cmd[1] == 'e') {cout << peek() << endl;}} else {cin >> x;sta.push(x);push(x);}}return 0;
}

#include<stdio.h>
#include<cstring>
#include<iostream>
#include<string>
using namespace std;  const int N=100005;
int c[N];  int lowbit(int i){  return i&(-i);
}  void add(int pos,int value){  while(pos<N){  c[pos]+=value;  pos+=lowbit(pos);  }
}  int sum(int pos){  int res=0;  while(pos>0){  res+=c[pos];  pos-=lowbit(pos);  }  return res;
}  int find(int value){  int l=0,r=N-1,median,res;  while(l<r-1){  if((l+r)%2==0)  median=(l+r)/2;  else  median=(l+r-1)/2;  res=sum(median);  if(res<value)  l=median;  else   r=median;  }  return l+1;
}  int main(){  //freopen("D://test.txt","r",stdin);  char ss[20];  int stack[N],top=0,n,pos;  memset(c,0,sizeof(c));  scanf("%d",&n);  while(n--){  scanf("%s",ss);  if(ss[1]=='u'){  scanf("%d",&pos);  stack[++top]=pos;  add(pos,1);  }else if(ss[1]=='o'){  if(top==0){  printf("Invalid\n");  continue;  }  int out=stack[top];  add(out,-1);  printf("%d\n",stack[top--]);  }else if(ss[1]=='e'){  if(top==0){  printf("Invalid\n");  continue;  }  int res;  if(top%2==0)  res=find(top/2);  else  res=find((top+1)/2);  printf("%d\n",res);  }else{  printf("Invalid\n");  }  }  return 0;
}