#include <cstdio>
#include <cstdlib>

#include <set>
#include <vector>
#include <iterator>
#include <algorithm>

using namespace std;

const char iname[] = "zeap.in";
const char oname[] = "zeap.out";

set <int> myset;
multiset <int> mymultiset;

inline int read(char *p)
{
	int n = 0;

	for (; *p < '0' || *p > '9'; ++ p) ;
	for (; '0' <= *p && *p <= '9'; ++ p)
		n = n * 10 + (*p - '0');
	return n;
}

int main(void)
{
	FILE *fi, *fo;
	char buffer[16];

	fi = fopen(iname, "r");
	fo = fopen(oname, "w");

	while (fgets(buffer, 16, fi))
	{
		char firstchar = buffer[0];
		char secondchar = buffer[1];

		if (firstchar == 'I')
		{
			int x = read(buffer);
			if (myset.size() > 0)
			{
				if (myset.find(x) == myset.end())
				{
					set <int>::iterator itup = myset.upper_bound(x), itlow;
					itlow = itup, itlow --;
			
					if (itup != myset.begin() && itup != myset.end())
						mymultiset.erase(mymultiset.find(*itup - *itlow));
					if (itup != myset.begin())
						mymultiset.insert(x - *itlow);
					if (itup != myset.end())
						mymultiset.insert(*itup - x);
			
					myset.insert(itlow, x);
				}
			} 
			else
				myset.insert(x);
		}
		if (firstchar == 'S')
		{
			int x = read(buffer);
			set <int>::iterator it = myset.find(x);
			if (it != myset.end())
			{
				set <int>::iterator itup = it, itlow = it;
				itup ++;
				itlow --;

				if (it != myset.begin())
					mymultiset.erase(mymultiset.find(x - *itlow));
				if (itup != myset.end())
					mymultiset.erase(mymultiset.find(*itup - x));
				if (it != myset.begin() && itup != myset.end())
					mymultiset.insert(*itup - *itlow);
	
				myset.erase(it);
			}
			else
				fprintf(fo, "-1\n");
		}
		if (firstchar == 'C')
		{
			int x = read(buffer);
			fprintf(fo, "%d\n", (myset.find(x) != myset.end() ? 1 : 0));
		}
		if (firstchar == 'M')
		{
			if (myset.size() > 1)
			{
				if (secondchar == 'A')
				{
					set <int>::iterator last = myset.end();
					last --;
					fprintf(fo, "%d\n", *last - *myset.begin());
				}
				else
					fprintf(fo, "%d\n", *mymultiset.begin());
			} 
			else
				fprintf(fo, "-1\n");
		}
	}

	fcloseall();

	return 0;
}