#include<fstream>
#include<vector>
#include<algorithm>
#include<queue>
#include<cstring>
#include<set>

#define NMAX 25
#define get_min(a,b) ((a)<(b)?(a):(b))

using namespace std; 

ifstream f("zeap.in");
ofstream g("zeap.out");

char line[NMAX];

priority_queue<int,vector<int>,greater<int> >  HEAP ,DA ;
set < int >  AVL;
int X , type ; 

inline void FindType ( void )
{
	bool ok = false ;
	if( line[0] == 'I' )
		type = 1 ;
	if( line[0] == 'S' )
		type = 2 ;
	if( line[0] == 'C' )
		type = 3 ;
    if( line[0] == 'M')
	{
		ok = true ; 
        if( line[1] == 'I' )
                type = 5 ; 
           else
				type = 4 ;
	}
	if ( ok == false )
	{
		for( int i(2) ; line[i] ; ++i )
			X=X*10+line[i]-'0';
	}
}
set < int > :: iterator it1 , it2 , it3;
int main ( void )
{
	
	while ( f.getline(line,25) )
	{
		X = 0 ;
		FindType();
		if( type == 1 )
		{
		pair < set<int>::iterator , bool > ok ;
		ok = AVL.insert(X) ;
		if( ok.second == 0 )
			continue ;
		if( AVL.size () == 2  )
		{
		  it1=it2=AVL.begin();
           ++it2;		  
		  HEAP.push(*it2-*it1);
		  continue ;
		}
		if( AVL.size()  <= 2 ) 
			continue ;
		it3 = ok.first ;
		if( it3 == AVL.begin () )
		{
			it1 = it3 ;
			it2 = ++ it1  ;
			HEAP.push( *it2 - *it3 );
			continue ;
		}
		
        it2 = it3 ;
        it1 = it2 ;
		--it1;
        ++it3;
		if( it3 == AVL.end() )
		{
			
			HEAP.push(*it2-*it1);
			continue;
		}
		
		HEAP.push(get_min( (*it3-*it2),(*it2-*it1)));
		
		continue ; 
		}
		else
			if( type == 2 )
			{
				if( AVL.empty() )
				{
					g<<-1<<"\n";
					continue;
				}
				it1 = AVL.end() ; 
				--it1 ; 
				it2 = AVL.find(X);
				if( it2 != AVL.end() )
				{
					if( AVL.size() == 1 )
					{
						AVL.erase(it2);
						continue ;
					}
					if( it2 == it1 )
					{
						it3 = --it2 ;
						++it2 ;
						DA.push(*it2-*it3);
						AVL.erase(it2);
						continue ; 
					}
					if( it2 == AVL.begin() )
					{
						it3 = ++it2 ; 
						--it2 ;
						DA.push(*it3-*it2);
						AVL.erase(it2);
						continue ; 
						
					}
					it3 = ++it2;
					--it2;
					it1 = --it2 ;
					++it2;
					DA.push(*it2-*it1);
					DA.push(*it3-*it2);
					HEAP.push(*it3-*it1);
					AVL.erase(it2);
					continue ;
				}
				else
				{
					g<<-1<<"\n";
					continue;
				}
			}
		else
			if( type == 3 )
				g<<(AVL.find(X)!=AVL.end())<<"\n";
		else
			if( type == 4 )
			{
				if( AVL.size() < 2 )
				{
					g<<-1<<"\n";
					continue;
				}
				it1 = AVL.end() ; 
				--it1;
				it2 = AVL.begin();
			 g<<*it1-*it2<<"\n";
			}

			else
				if( type == 5 )
				{
					if( AVL.size() < 2 )
				{
					g<<-1<<"\n";
					continue;
				}
					while ( !DA.empty() && DA.top() == HEAP.top() )
					{
								HEAP.pop();
								DA.pop();
					}
		  g<<HEAP.top()<<"\n";
				}
	}
	f.close();
	g.close();
	return 0 ;
}