#include <cstdio>
#include <set>
#include <map>

using namespace std;

const int BMAX = 16;

map <int, int> S;
multiset <int> Min;

inline int ABS(int x) { return x < 0 ? -x : x; }

inline int toint(char s[]) {
	int rez = 0, i;
	for (i = 0; isdigit(s[i]); ++i)
		rez = rez * 10 + s[i] - '0';
	return rez;
}

inline void sterg(map <int, int> :: iterator it) {
	int a, b, c = 0;

	a = it->first;

	if (it->second == 1) ++c, it->second = 0;

	++it;
	if (it->second == -1) ++c, it->second = 0;
	b = it->first;

	while (c) 
		Min.erase( Min.find( ABS(a - b) ) ),
		--c;
}

inline void leaga(map <int, int> :: iterator it) {
	map <int, int> :: iterator j;
	int a, b, c;
	b = c = -1;
	a = it->first;
	
	if (it != S.begin()) {
		j = it;
		--j;
		b = j->first;
	}
	
	j = it; ++j;
	if (j != S.end())
		c = j->first;

	if (c == -1 && b == -1) {
		it->second = 0;
		return;
	}
	if (c == -1) {
		it->second = -1;
		Min.insert( ABS(a - b) );
		return;
	}
	if (b == -1) {
		it->second = 1;
		Min.insert( ABS(a - c) );
		return;
	}
	it->second = ABS(a - b) < ABS(a - c) ? -1 : 1;
	Min.insert(it->second == -1 ? ABS(a - b) : ABS(a - c));
}

int main() {
	FILE *fin = fopen("zeap.in", "rt");
	FILE *fout = fopen("zeap.out", "wt");
	char buf[BMAX];
	map <int, int> :: iterator it;
	int aux;
	
	while (fgets(buf, BMAX, fin)) {
		switch (buf[0]) {
			case 'I':
				aux = toint(buf + 2);
				if (S.find(aux) == S.end()) {
					it = S.lower_bound(aux);
					if (it != S.end() && it != S.begin()) 
						sterg(--it);
					
					S[aux] = 0;
					it = S.find(aux);

					leaga(it);
				}
				break;
			case 'S':
				aux = toint(buf + 2);
				if ((it = S.find(aux)) != S.end()) {
					sterg(it);
					if (it != S.begin())
						sterg(--it),
						++it;
					S.erase(it);

					if (S.size() >= 2) {
						it = S.lower_bound(aux);
						if (it != S.end() && it->second == 0)
							leaga(it);
						if (it != S.begin())
							if (--it->second == 0)
								leaga(it);
					}
				} else
					fprintf(fout, "-1\n");
				break;
			case 'C':
				aux = toint(buf + 2);
				if (S.find(aux) != S.end())
					fprintf(fout, "1\n");
				else
					fprintf(fout, "0\n");
				break;
			case 'M':
				if (S.size() < 2)
					fprintf(fout, "-1\n");
				else if (buf[1] == 'A')
					fprintf(fout, "%d\n", S.rbegin()->first - S.begin()->first);
				else
					fprintf(fout, "%d\n", *Min.begin());
				break;
		}
	}

	fclose(fin);
	fclose(fout);
	return 0;
}