#include <stdio.h>
#include <iostream>
using namespace std;

int main()
{
    int k,n,x,left=0,right=0,isEmpty=0;
    cin>>n;
    int a[n];
    for(int l=0;l<=n;l++){
        a[l]  = 0;
    }
    for(int i=0;i<n;i++){
        cin>>k;
        if(k==1){
            cin>>x;
            a[right] = x;
            right++;
            isEmpty++;
        }
        if(k==2){
            if(isEmpty>0) cout<<a[left]<<endl;
            else cout<<"-1"<<endl;
        }
        if(k==3){
            if(isEmpty>0){
                a[left] =0;
                isEmpty--;
                left++;
            }
        }
        /*for(int j=0;j<n;j++){
            cout<<a[j]<<" ";
        }
        cout<<endl;*/
    }
    return 0;
}
//AC 0.2s 720KB