#include <cstdio>
#include <iostream>
#include <stdlib.h>
#include <time.h>
#define INF 2147483647
using namespace std;
char buff[6000010];
int poz=0;
int getnr(){
    int nr=0;
    while ('0'>buff[poz] || buff[poz]>'9')
        poz++;
    while ('0'<=buff[poz] && buff[poz]<='9'){
        nr=nr*10+buff[poz]-'0';
        poz++;
    }
    return nr;
}
struct treap{
    int key;
    int pri;
    int mindif;
    int maxi;
    int mini;
    int subarb;
    treap *st,*dr;

    treap (int key,int pri,treap *st,treap *dr,int mindif,int maxi,int mini){
        this->key=key;
        this->pri=pri;
        this->st=st;
        this->dr=dr;
        this->mindif=mindif;
        this->maxi=maxi;
        this->mini=mini;
    }
};
treap *r,*nil;
void update (treap *&n){ /// update valorilor din n
    n->maxi = max(n->key,max(n->st->maxi,n->dr->maxi));
    n->mini = min(n->key,min(n->st->mini,n->dr->mini));
    int sol=INF;
    if (n->dr->mini != INF)
        sol=min(sol,n->dr->mini - n->key);
    if (n->st->maxi != -INF)
        sol=min(sol,n->key - n->st->maxi);
    n->mindif = min(sol,min(n->st->mindif,n->dr->mindif));
}
int cauta (treap *n,int key){
    if (n==nil)
        return 0;
    else if (n->key==key)
        return 1;
    else if (n->key<key)
        return cauta (n->dr,key);
    else return cauta (n->st,key);
}
void left (treap *&n){
    treap *y = n->st;

    n->st = y->dr;
    y->dr=n;
    n=y;
    update (n->dr);
    update (n);
}
void right (treap *&n){
    treap *y = n->dr;

    n->dr = y->st;
    y->st=n;
    n=y;
    update (n->st);
    update (n);
}
void balance (treap*&n){
    if (n->pri < n->st->pri) /// rotire stanga
        left (n);

    else if (n->pri < n->dr->pri) /// rotire dreapta
        right(n);
}

void inser (treap *&n,int key,int pri){
    //if (key==3)
      //  printf ("a");
    if (n==nil){ /// e mom sa il adaug?
         n = new treap (key,pri,nil,nil,INF,key,key);
         return;
    }
    else {
        if (key < n->key)
            inser (n->st, key,pri);
        else
            inser (n->dr,key,pri);
    }

    balance (n);
    if (n!=nil)
        update (n); /// update valorile lui n ???

}

void eras (treap *&n,int key){
    if (n==nil)
        return;
    if (key < n->key)
        eras (n->st, key);
    else if (key > n->key)
        eras (n->dr,key);
    else { /// l am gasit, il mut in jos pana e frunza
        if (n->st == nil && n->dr == nil){ /// e frunza
            delete n;
            n=nil;
        }
        else { /// erase ca la heap
            if (n->st->pri > n->dr->pri)
                left(n);
            else right(n);
            eras (n,key);
        }
    }
    if (n!=nil)
        update (n); /// update valorile lui n ???
}
int main()
{
    FILE *fin=fopen ("zeap.in","r");
    FILE *fout=fopen ("zeap.out","w");
    int x,tot=0;
    srand (time(0));
    r=nil=new treap(0,0,NULL,NULL,INF,-INF,INF);
    fread(buff,1,6000000,fin);
    while (buff[poz]!=0){
        while ('A'>buff[poz] || 'Z'<buff[poz])
            poz++;
        if (buff[poz]==0)
            break;
        if (buff[poz]=='I'){
            poz++;
            x=getnr();
            //printf ("a");
            if (!cauta(r,x)){ /// daca x nu exista deja in treap
                inser (r,x,rand()+1);
                tot++;
            }
            /// insert x in treap
        }
        else if (buff[poz]=='S'){
            poz++;
            x=getnr();
            //printf ("n");
            if (!cauta(r,x)){ /// daca nu exista
                fprintf (fout,"-1\n");
            }
            else{
                eras (r,x); /// sterge x din treap
                tot--;
            }
        }
        else if (buff[poz]=='C'){
            poz++;
            x=getnr();
            fprintf (fout,"%d\n",cauta(r,x));
        }
        else {
            if (tot <2)
                fprintf (fout,"-1\n");
            else{
                if (buff[poz+1]=='A')
                    fprintf (fout,"%d\n",r->maxi - r->mini);
                else fprintf (fout,"%d\n",r->mindif);
            }
            poz+=3;
        }
    }
    return 0;
}