#include <bits/stdc++.h>

using namespace std;

ifstream in("zeap.in");
ofstream out("zeap.out");

set <int> zeap;

int main(){

    string op;
    int val;

    while(in>>op){
        if(op=="I"){
            in>>val;
            zeap.insert(val);

        }
        else if(op=="S"){
            in>>val;
            if (zeap.find(val)==zeap.end())
                out<<-1<<"\n";
            else
                zeap.erase(val);
        }
        else if(op=="C"){
            in>>val;
            if (zeap.find(val)==zeap.end())
                out<<0<<"\n";
            else
                out<<1<<"\n";
        }
        else if(op=="MAX"){
            if(zeap.size()<2)
                out<<0<<"\n";
            else{
                auto mm = zeap.begin();
                auto mn = zeap.end();

                mm = prev(mm,1);
                out<<*mm-*mn<<"\n";
            }
        }
        else if(op=="MIN"){
            if(zeap.size()<2)
                out<<0<<"\n";
            else{
                auto mm = zeap.begin();
                auto mn = next(mm,1);

                out<<*mm-*mn<<"\n";
            }
        }
    }
    return 0;
}