#include<iostream>
#include<set>
#include<string>
using namespace std;
int n, q;
int main() {
	cin >> n >> q;
	string flag; int pos1, pos2; set<int>tree;
	for (int i = 0; i < q; i++) {
		cin >> flag;
		if (flag == "-") {
			cin >> pos1;
			tree.insert(pos1);
		}
		else if (flag == "+") {
			cin >> pos1;
			tree.erase(pos1);
		}
		else {
			cin >> pos1 >> pos2;
			if (pos1 > pos2) {
				int tmp = pos1;
				pos1 = pos2;
				pos2 = tmp;
			}
			if (tree.size() == 0) {
				cout << "possible" << endl;
			}
			else {
				set<int>::iterator iters = tree.lower_bound(pos2);
				set<int>::iterator iters_1 = --iters; ++iters;
				set<int>::iterator iters_2 = tree.lower_bound(pos1);
				if ((iters != tree.end() || (iters_2 != tree.end() && *iters_2 == pos1) || iters_2 != tree.begin()) && (iters != tree.begin() && *iters_1 >= pos1))
					cout << "impossible" << endl;
				else
					cout << "possible" << endl;
			}
		}
	}
	return 0;
}