queue

#include<iostream>
#include<queue>

using namespace std;

main()
{
    queue <int> Q;
    int n;
    cin>>n;
    for(int i=0; i<n; i++)
    {
        int x;
        cin>>x;
        if(x == 1)
        {
            cout<<Q.size()<<endl;
        }
        if(x == 2)
        {
            if(!Q.empty()) cout<<"NO";
            else cout<<"YES";
            cout<<endl;
        }
        if(x == 3)
        {
            int a;
            cin>>a;
            Q.push(a);
        }
        if(x == 4)
        {
            if(!Q.empty()) Q.pop();
        }
        if(x == 5)
        {
            if(!Q.empty()) cout<<Q.front();
            else cout<<"-1";
            cout<<endl;
        }
        if(x == 6)
        {
            if(!Q.empty()) cout<<Q.back();
            else cout<<"-1";
            cout<<endl;
        }
    }
}