#include <iostream>
#include <fstream>
#include <ctime>
#include <random>
#include <string>

using namespace std;

const int INF = 1000000000;

class Treap
{
public:
    struct nod
    {
        int mn, mx, difMin;
        int val, priority;
        nod *fiuSt, *fiuDr;
    };
    Treap(nod *root = nullptr)
    {
        this->root = root;
        srand(time(0));
    }
    void Insert(int val)
    {
        Insert(root, rand(), val);
    }
    void Split(int val, Treap &st, Treap &dr)
    {
        nod *retSt, *retDr;
        Split(root, val, retSt, retDr);
        st = Treap(retSt);
        dr = Treap(retDr);
    }
    //that > this
    void Join(Treap &that)
    {
        root = Join(root, that.root);
        that = Treap();
    }
    void Erase(int val)
    {
        Erase(root, val);
    }
    bool Find(int val)
    {
        return Find(root, val);
    }
    int MaxDif()
    {
        return root->mx - root->mn;
    }
    int MinDif()
    {
        return root->difMin;
    }
private:
    void Update(nod * x)
    {
        if(x != nullptr)
        {
            x->mn = x->mx = x->val;
            x->difMin = INF;
            if(x->fiuSt != nullptr)
            {
                x->mn = min(x->mn, x->fiuSt->mn);
                x->difMin = min(x->difMin, min(x->fiuSt->difMin, x->val - x->fiuSt->mx));
            }
            if(x->fiuDr != nullptr)
            {
                x->mx = max(x->mx, x->fiuDr->mx);
                x->difMin = min(x->difMin, min(x->fiuDr->difMin, x->fiuDr->mn - x->val));
            }
        }
    }
    void Split(nod *current, int val, nod * &st, nod * &dr)
    {
        if(current == nullptr)
            st = dr = nullptr;
        else if(val < current->val)
        {
            dr = current;
            Split(current->fiuSt, val, st, current->fiuSt);
        }
        else
        {
            st = current;
            Split(current->fiuDr, val, current->fiuDr, dr);
        }
        Update(current);
    }
    nod * Join(nod * st, nod * dr)
    {
        if(st == nullptr)
            return dr;
        if(dr == nullptr)
            return st;
        if(st->priority >= dr->priority)
        {
            st->fiuDr = Join(st->fiuDr, dr);
            Update(st);
            return st;
        }
        dr->fiuSt = Join(st, dr->fiuSt);
        Update(dr);
        return dr;
    }
    void Insert(nod * &current, int priority, int val)
    {
        if(current == nullptr || priority > current->priority)
        {
            nod * st, * dr;
            Split(current, val, st, dr);
            current = new nod;
            current->val = val, current->priority = priority;
            current->fiuSt = st, current->fiuDr = dr;
            Update(current);
            return;
        }
        if(val < current->val)
            Insert(current->fiuSt, priority, val);
        else
            Insert(current->fiuDr, priority, val);
        Update(current);
    }
    void Erase(nod * &current, int val)
    {
        if(val == current->val)
        {
            nod * t = current;
            current = Join(current->fiuSt, current->fiuDr);
            delete t;
            Update(current);
            return;
        }
        if(val < current->val)
            Erase(current->fiuSt, val);
        else
            Erase(current->fiuDr, val);
        Update(current);
    }
    bool Find(nod * current, int val)
    {
        if(current == nullptr)
            return false;
        if(val == current->val)
            return true;
        if(val < current->val)
            return Find(current->fiuSt, val);
        return Find(current->fiuDr, val);
    }
    nod * root;
};

int main()
{
    ifstream in("zeap.in");
    ofstream out("zeap.out");
    string type;
    int x;
    Treap treap;
    int elem = 0;
    while(in >> type)
    {
        if(type == "I")
        {
            in >> x;
            if(treap.Find(x) == false)
            {
                treap.Insert(x);
                elem++;
            }
        }
        else if(type == "S")
        {
            in >> x;
            if(treap.Find(x) == false)
                out << -1 << "\n";
            else
            {
                treap.Erase(x);
                elem--;
            }
        }
        else if(type == "C")
        {
            in >> x;
            out << treap.Find(x) << "\n";
        }
        else if(type == "MAX")
        {
            if(elem >= 2)
                out << treap.MaxDif() << "\n";
            else
                out << -1 << "\n";
        }
        else
        {
            if(elem >= 2)
                out << treap.MinDif() << "\n";
            else
                out << -1 << "\n";
        }
    }
    in.close();
    out.close();
    return 0;
}