#include <bits/stdc++.h>

using namespace std;

const int INF = 1e9;

struct Treap {
  int value;
  long long priority;
  Treap* left;
  Treap* right;
  int mx;
  int mn;
  int dif;
}*root;

Treap* emptyTreap = new Treap {0, 0, NULL, NULL, -INF, INF, INF};

Treap* jonule (Treap* root) {
  if (root == emptyTreap)
    return emptyTreap;
  root -> mn = min(root->value, min(root->left->mn, root->right->mn));
  root -> mx = max(root->value, max(root->left->mx, root->right->mx));
  int t1, t2;
  t1 = t2 = INF;
  if (root ->left != emptyTreap)
    t1 = root->value - root->left->mx;
  if (root->right != emptyTreap)
    t2 = root->right->mn - root->value;
  root->dif = min(min(t1, t2), min(root->left->dif, root->right->dif));
  return root;
}

pair<Treap*, Treap*> split (Treap* root, int x) {
  if (root == emptyTreap)
    return {emptyTreap, emptyTreap};
  if (root->value <= x) {
    auto p = split(root->right, x);
    Treap* hatz = new Treap {root->value, root->priority, root->left, p.first, 0, 0, 0};
    hatz = jonule(hatz);
    p.second = jonule(p.second);
    return {hatz, p.second};
  }
  if (root->value > x) {
    auto p = split(root->left, x);
    Treap* hatz = new Treap {root->value, root->priority, p.second, root->right, 0, 0, 0};
    hatz = jonule(hatz);
    p.first = jonule(p.first);
    return {p.first, hatz};
  }
}


Treap* merge (Treap *first, Treap* second) {
  if (first == emptyTreap)
    return second;
  if (second == emptyTreap)
    return first;
  if (second ->priority < first->priority) {
    auto p = merge(first -> right, second);
    Treap * hatz = new Treap {first->value,first->priority, first->left, p, 0, 0, 0};
    hatz = jonule(hatz);
    return hatz;
  }
  else if (second ->priority >= first->priority) {
    auto p =merge(first, second->left);
    Treap* hatz = new Treap {second->value, second->priority, p, second->right, 0, 0, 0};
    hatz = jonule(hatz);
    return hatz;
  }
}

int sz = 0;

Treap* insert(Treap* root, int value) {
  sz++;
  Treap* newV = new Treap {
    value,
    ((long long)rand() << 31) | rand(),
    emptyTreap,
    emptyTreap,
    value,
    value,
    INF,
  };
  auto p = split(root, value);
  Treap* t = merge(merge(p.first, newV) ,p.second);
  return t;
}

Treap* erase (Treap* root, int value) {
  sz--;
  auto p1 = split(root, value);
  auto p2 = split(p1.second, value + 1);
  return merge(p1.first, p2.second);
}

bool find (Treap* root, int value) {
  if(root == emptyTreap)
    return 0;
  if(value == root->value)
    return 1;
  if(value < root->value)
    return find(root->left, value);
  else
    return find(root->right, value);
}


int n, q, v[100002], x, t;



int main()
{
  root = emptyTreap;
  while (1) {
    string s;
    cin >> s;
    if (!s.size())
      break;
    if (s == "I") {
      cin >> x;
      if (!find(root, x))
        root = insert(root, x);
    }
   else if (s == "S") {
      cin >>x;
      if (!find(root, x))
        cout << "-1\n";
      else
        root = erase(root, x);
    }
    else if (s == "C") {
      cin >> x;
      cout << find(root, x) << "\n";
    }
    else if (s == "MAX") {
      if (sz < 2)
        cout << "-1\n";
      else
        cout << root -> mx - root ->mn << "\n";
    }
    else if (s == "MIN") {
      if (sz < 2)
        cout << "-1\n";
      else
        cout << root->dif << "\n";
    }
    else
      break;
  }
  return 0;
}