#include <bits/stdc++.h>
#define MOD 666013
using namespace std;
int x,nr;
char c;
struct Treap
{
    int key,pr;
    Treap *l,*r;
    int ma,mi,dif;
    Treap(int key1,int pr1,int ma1,int mi1,int dif1,Treap *l1,Treap *r1)
    {
        key=key1;
        pr=pr1;
        ma=ma1;
        mi=mi1;
        dif=dif1;
        l=l1;
        r=r1;
    }
}*R,*nil;
void Update(Treap *&R)
{
    R->ma=max(R->key,R->r->ma);
    R->mi=min(R->key,R->l->mi);
    R->dif=min(min(R->l->dif,R->r->dif),min(abs(R->key-R->l->ma),abs(R->key-R->r->mi)));
}
void rotleft(Treap *&R)
{
    Treap *aux=R->l;
    R->l=aux->r;
    aux->r=R;
    R=aux;
    if(R!=nil)
    {
        if(R->r!=nil)Update(R->r);
    }
}
void rotright(Treap *&R)
{
    Treap *aux=R->r;
    R->r=aux->l;
    aux->l=R;
    R=aux;
    if(R!=nil)
    {
        if(R->l!=nil)Update(R->l);
    }
}
void balance(Treap *&R)
{
    if(R->pr<R->l->pr)rotleft(R);
    else if(R->pr>R->r->pr)rotright(R);
    Update(R);
}
bool Cauta(Treap *&R,int val)
{
    if(R==nil)return 0;
    if(R->key==val)return 1;
    if(R->key>val)return Cauta(R->l,val);
    if(R->key<val)return Cauta(R->r,val);
}
void Insereaza(Treap *&R,int val,int pr)
{
    if(R==nil)
    {
        R=new Treap(val,pr,val,val,INT_MAX,nil,nil);
        nr++;
        return ;
    }
    if(val<R->key)Insereaza(R->l,val,pr);
    else if(val>R->key)Insereaza(R->r,val,pr);
    balance(R);
}
void Sterge(Treap *&R,int val)
{
    if(val<R->key)Sterge(R->l,val);
    else if(val>R->key)Sterge(R->r,val);
    else
    {
        if(R->r==nil&&R->l==nil)
        {
            delete R;
            R=nil;
            --nr;
            return ;
        }
        else
        {
            if(R->l->pr>R->r->pr)rotleft(R);
            else rotright(R);
            Sterge(R,val);
        }
    }
    if(R!=nil)Update(R);
}
int main()
{
    ifstream f ("zeap.in");
    ofstream g ("zeap.out");
    srand(time(0));
    R=nil=new Treap(0,0,INT_MIN,INT_MAX,INT_MAX,NULL,NULL);
    while(f>>c)
        if(c=='I')
        {
            f>>x;
            if(!Cauta(R,x))Insereaza(R,x,rand()%MOD+1);
        }
        else if(c=='S')
        {
            f>>x;
            if(!Cauta(R,x))g<<-1<<'\n';
            else Sterge(R,x);
        }
        else if(c=='C')
        {
            f>>x;
            if(Cauta(R,x))g<<1<<'\n';
            else g<<0<<'\n';
        }
        else if(c=='M')
        {
            f>>c;
            f>>c;
            if(nr<2)
            {
                g<<-1<<'\n';
                continue;
            }
            if(c=='N')g<<R->dif<<'\n';
            else g<<R->ma-R->mi<<'\n';
        }
    return 0;
}