#include <bits/stdc++.h>
using namespace std;
ifstream f("zeap.in");
ofstream g("zeap.out");
#define cin f
#define cout g

struct Node
{
	int key;
	Node *left;
	Node *right;
	Node *father;
};
Node *createNode(int key)
{
	Node *node = new Node();
	node->key = key;
	node->left = NULL;
	node->right = NULL;
	node->father = NULL;
	return node;
}
void search(Node *node)
{
	if(node == NULL)
		return;
	queue < Node * > q;
	q.push(node);
	while(! q.empty())
	{
		Node *temp = q.front();
		q.pop();
		cout<<"Node: "<<temp->key<<'\n';
		if(temp->left != NULL)
		{
			q.push(temp->left);
			cout<<"Left: "<<temp->left->key<<'\n';
		}
		else
			cout<<"Left: NULL\n";
		if(temp->right != NULL)
		{
			q.push(temp->right);
			cout<<"Right: "<<temp->right->key<<'\n';
		}
		else
			cout<<"Right: NULL\n";
	}
}

struct Tree
{
	int n = 0;
	Node *root = NULL;
};
Node *TreeMinimum(Node *node)
{
	while(node->left != NULL)
		node = node->left;
	return node;
}
Node *TreeMaximum(Node *node)
{
	while(node->right != NULL)
		node = node->right;
	return node;
}
Node *TreeSearch(Node *node, int x)
{
	while(node != NULL and x != node->key)
		if(x < node->key)
			node = node->left;
		else
			node = node->right;
	return node;
}
Node *TreeSuccessor(Node *node1)
{
	if(node1->right != NULL)
		return TreeMinimum(node1->right);
	Node *node2 = node1->father;
	while(node2 != NULL and node1 == node2->right)
	{
		node1 = node2;
		node2 = node2->father;
	}
	return node2;
}
Node *TreePredecessor(Node *node1)
{
	if(node1->left != NULL)
		return TreeMaximum(node1->left);
	Node *node2 = node1->father;
	while(node2 != NULL and node1 == node2->left)
	{
		node1 = node2;
		node2 = node2->father;
	}
	return node2;
}
void TreeInsert(Tree &T, int key)
{
	T.n ++;
	Node *newNode = createNode(key);
	Node *father = NULL, *root = T.root;
	while(root != NULL)
	{
		father = root;
		if(newNode->key < root->key)
			root = root->left;
		else
			root = root->right;
	}
	newNode->father = father;
	if(father == NULL)
		T.root = newNode;
	else if(newNode->key < father->key)
		father->left = newNode;
	else
		father->right = newNode;
}
void TreeDelete(Tree &T, Node *node)
{
	T.n --;
	Node *x, *y;
	if(node->left == NULL or node->right == NULL)
		y = node;
	else
		y = TreeSuccessor(node);
	if(y->left != NULL)
		x = y->left;
	else
		x = y->right;
	if(x != NULL)
		x->father = y->father;
	if(y->father == NULL)
		T.root = x;
	else if(y == y->father->left)
		y->father->left = x;
	else
		y->father->right = x;
	if(y != node)
		node->key = y->key;
	delete y;
}

int main()
{
	Tree t;
	string s;
	while(cin >> s)
	{
		int x;
		if(s[0] == 'I')
		{
			cin >> x;
			TreeInsert(t, x);
		}
		else if(s[0] == 'S')
		{
			cin >> x;
			Node *node = TreeSearch(t.root, x);
			if(node == NULL)
				cout<<-1<<'\n';
			else
				TreeDelete(t, node);
		}
		else if(s[0] == 'C')
		{
			cin >> x;
			Node *node = TreeSearch(t.root, x);
			if(node == NULL)
				cout<<0<<'\n';
			else
				cout<<1<<'\n';
		}
		else if(s[1] == 'A')
		{
			if(t.n > 1)
				cout<<TreeMaximum(t.root)->key - TreeMinimum(t.root)->key<<'\n';
			else
				cout<<-1<<'\n';
		}
		else
		{
			if(t.n > 1)
			{
				int mn = 1e9 + 1;
				Node *first, *second;
				first = TreeMinimum(t.root);
				second = TreeSuccessor(first);
				while(second != NULL)
				{
					mn = min(mn, second->key - first->key);
					first = second;
					second = TreeSuccessor(first);
				}
				cout<<mn<<'\n';
			}
			else
				cout<<-1<<'\n';
		}
	}
	return 0;
}