#include <bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	stack<int> sa,sb;
	for(int i=1;i<=n;++i){
		int x;
		scanf("%d",&x);
		if(x==0){
			int y;
			scanf("%d",&y);
			sa.push(y);
			if(i==1) sb.push(y);
			else sb.push(max(y,sb.top()));
		}
		else if(x==1){
			if(!sa.empty()){
				sa.pop();
				sb.pop();
			}	
		}
		else{
			if(!sb.empty()){
				cout<<sb.top()<<endl;
			}
			else cout<<0<<endl;
		}
	} 
	return 0;
}