先进先出

#include<iostream>

#include<algorithm>

#include<cstdio>

#include<stack>

#include<string.h>

#include<string>

#include<vector>

#include<queue>

#include<map>

#include<set>

using namespace std;

int main(){

	queue<char> q;

	int n;

	char x;

	cin>>n;

	for(int i=0;i<n;i++){

		cin>>x;

		q.push(x);

	}

	cout<<q.size()<<endl;

	 cout<<q.empty()<<endl;

	 cout<<q.front()<<endl;

	 cout<<q.back()<<endl;

	  while(!q.empty()){

	  	cout<<q.front()<<endl;

	  	q.pop();

	  }

	return 0;

}