#include<iostream>
using namespace std;
class str{
	private:
		int num[100005],w=0;
	public:
		void push(int x){
			w++;
			num[w]=x;
		}
		void pop(){
			w--;
		}
		int top(){
			return num[w];
		}
		int getmin(){
			int minn=INT_MAX;
			for(int i=1;i<=w;i++) minn=min(minn,num[i]);
			return minn;
		}
}a;
void change(int x){
	switch(x){
		case 1: 
			int y;
			cin>>y;
			a.push(y);
			break;
		case 2: 
			a.pop();
			break;
		case 3: 
			cout<<a.top()<<endl;
			break;
		case 4: 
			cout<<a.getmin()<<endl;
			break;
	}
}
int n;
int main(){
	std::ios::sync_with_stdio(false);
	cin>>n;
	for(int i=1;i<=n;i++){
		int x;
		cin>>x;
		change(x);
	}
}