#include <bits/stdc++.h>
using namespace std;

int main(){
	int n;
	scanf("%d", &n);
	set<int> s;
	for(int i = 0; i < n; i++) {
		int id, x;
		scanf("%d%d", &id, &x);
		if(id == 0) {
			s.insert(x);
			printf("%lu\n", s.size());
		}else if(id == 1) {
			printf("%lu\n", s.count(x));
		}else if(id == 2) {
			s.erase(x);
		}
	}
}

