#include <iostream>
#include<bits/stdc++.h>

using namespace std;

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

set<long long>zp; //in acest set retin in ordine crescatoare toate valorile din zeap. Astfel pot rezolva toate operatiile mai putin cea de diferenta minima
bool v[1000000000]={0};

struct diferenta{

long long x,y;//perechi de forma predecesor valoare sau valoare succesor
long long mini;


};

struct pereche{

long long prim,sec;

};

pereche vecini(set<long long> s,long long x)
{
    pereche aux;
    aux.prim = -1;
    aux.sec = -1;
    set<long long>::iterator it = s.find(x);
    if(it!=s.begin())
    {
        it--;
        aux.prim = *it;
        it++;
    }
    it++;
    if(it!=s.end())
    {

        aux.sec = *it;
    }
    return aux;
}

struct compare_mini{
bool operator()(diferenta const& d1, diferenta const& d2)
{
    return d1.mini > d2.mini;
}

};

priority_queue<diferenta,vector<diferenta>,compare_mini> pq;




int main()
{
    string com;
    while(fin>>com)
    {
        if(com == "I")
        {
            int x;
            fin>>x;
            if(v[x]==0)
            {
                zp.insert(x);
                v[x] = 1;
                pereche aux2 = vecini(zp,x);
                diferenta aux3,aux4;
                if(aux2.prim!=-1)
                {
                    aux3.x = aux2.prim;
                    aux3.y = x;
                    aux3.mini = x- aux2.prim;
                    pq.push(aux3);
                }
                if(aux2.sec != -1)
                {
                    aux4.x = x;
                    aux4.y = aux2.sec;
                    aux4.mini = aux2.sec - x;
                    pq.push(aux4);
                }
            }
        }
        if(com == "S")
        {
            int x;
            fin>>x;
            if(v[x] == 0)
                fout<<-1<<"\n";
            else
             {
                 if(vecini(zp,x).prim!=-1 && vecini(zp,x).sec!=-1)
                 {
                     diferenta aux5;
                     aux5.x = vecini(zp,x).prim;
                     aux5.y = vecini(zp,x).sec;
                     aux5.mini = aux5.y - aux5.x;
                     pq.push(aux5);
                 }
                 v[x] = 0;
                 zp.erase(x);
             }
        }
        if(com == "C")
        {
            int x;
            fin>>x;
            if(v[x]==0)
                fout<<0<<"\n";
            else
                fout<<1<<"\n";
        }
        if(com == "MAX")
        {

            if(zp.size()<2)
                fout<<-1<<"\n";
            else
            {
                set<long long>::iterator it = zp.begin();
                set<long long>::iterator it2 = zp.end();
                it2--;
                fout<<abs(*it - *it2)<<"\n";
            }
        }
        if(com == "MIN")
        {

            if(zp.size()<2)
                fout<<-1<<"\n";
            else
            {
                while(!pq.empty() && (v[pq.top().x] == 0|| v[pq.top().y]== 0))
                    pq.pop();
             fout<<pq.top().mini<<"\n";
            }

        }
    }


	return 0;

}