#include<fstream>
#include<iostream>
#include<map>
#include<algorithm>
using namespace std;
ifstream fin("zeap.in");
ofstream fout("zeap.out");
map<int,bool> v;
char x[5];
int n;
int main()
{
	while(fin>>x)
	{
		if(x[0]=='I')
		{
			fin>>n;
			v.insert(pair<int,bool>(n,1));
			continue;
		}
		if(x[0]=='S')
		{
			fin>>n;
			if(!v.erase(n))
				fout<<-1<<'\n';
			continue;
		}
		if(x[0]=='M')
		{
			if(v.size()<2)
			{
				fout<<-1<<'\n';
				continue;
			}
			if(x[1]=='A')
			{
				map<int,bool>::iterator it1,it2;
				it1=v.end();
				it1--;
				it2=v.begin();
				fout<<(*it1).first-(*it2).first<<'\n';
			}
			else
			{
				int minim=(1<<30);
				map<int,bool>::iterator it1=v.begin(),it2;
				it2=it1++;
				for(;it1!=v.end();it1++,it2++)
					minim=min(minim,(*it1).first-(*it2).first);
				fout<<minim<<'\n';
			}
			continue;
		}
		if(x[0]=='C')
		{
			fin>>n;
			fout<<(v.find(n)!=v.end())<<'\n';
		}
	}
	fin.close();
	fout.close();
	return 0;
}