#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <cassert>

using namespace std;

const int INF = 0x7fffffff;

struct node {
   int p;
   int v;
   int vmin;
   int vmax;
   int difmin;
   int siz;
   node *left;
   node *right;
};

node *defNode = new node{0, 0, 0, 0, INF, 0, NULL, NULL};

node *makeNode(node *old, node *left, node *right) {
   old->vmin = (left == defNode ? old->v : left->vmin);
   old->vmax = (right == defNode ? old->v : right->vmax);
   old->difmin = min(left->difmin, right->difmin);
   if(left != defNode) old->difmin = min(old->difmin, old->v - left->vmax);
   if(right != defNode) old->difmin = min(old->difmin, right->vmin - old->v);
   old->siz = left->siz + 1 + right->siz;
   old->left = left;
   old->right = right;
   return old;
}

pair<node*, node*> split(node *t, int v) {
   if(t == defNode) return make_pair(defNode, defNode);
   node *left, *right;
   pair<node*, node*> s;
   if(t->v < v) {
      s = split(t->right, v);
      left = makeNode(t, t->left, s.first);
      right = s.second;
   }
   else {
      s = split(t->left, v);
      left = s.first;
      right = makeNode(t, s.second, t->right);
   }
   return make_pair(left, right);
}

node *join(node *left, node *right) {
   if(left == defNode) return right;
   if(right == defNode) return left;
   if(left->p <= right->p)
      return makeNode(left, left->left, join(left->right, right));
   else
      return makeNode(right, join(left, right->left), right->right);
}

node *ins(node *t, int v) {
   node *newNode = new node{rand(), v, v, v, INF, 1, defNode, defNode};
   pair<node*, node*> s = split(t, v);
   return join(join(s.first, newNode), s.second);
}

node *del(node *t, int v) {
   pair<node*, node*> s = split(t, v);
   return join(s.first, split(s.second, v + 1).second);
}

bool fnd(node *t, int v) {
   if(t == defNode) return 0;
   if(v < t->v) return fnd(t->left, v);
   if(v > t->v) return fnd(t->right, v);
   return 1;
}

int main() {
   freopen("zeap.in", "r", stdin);
   freopen("zeap.out", "w", stdout);

   int i, x, y;
   char c1, c2, c3;

   srand(time(NULL));
   node *t = defNode;

   while(scanf("%c", &c1) != EOF) {
      if(c1 == 'M') {
         scanf("%c%c\n", &c2, &c3);
         if(c2 == 'I') {
            y = (t->siz < 2 ? -1 : t->difmin);
         }
         if(c2 == 'A') {
            y = (t->siz < 2 ? -1 : t->vmax - t->vmin);
         }
      }
      else {
         scanf("%d\n", &x);
         if(c1 == 'I') {
            if(!fnd(t, x)) {
               t = ins(t, x);
            }
            y = INF;
         }
         if(c1 == 'S') {
            if(fnd(t, x)) {
               t = del(t, x);
               y = INF;
            }
            else {
               y = -1;
            }
         }
         if(c1 == 'C') {
            y = fnd(t, x);
         }
      }

      if(y != INF) {
         printf("%d\n", y);
      }
   }

   return 0;
}