第1个样例就没过

#include<bits/stdc++.h>
using namespace std;
int n;
string s;
deque<string> q;
int id=1;
void start()
{
	if(id!=1)
	{
		if(q.size()==1)
		{
			cout<<q.front()<<endl;
		}
		else
		{
			for(int i=1;i<=2;i++)
			{
				cout<<q.front()<<" ";
				q.push_back(q.front());
				q.pop_front();
			}
		}
	}
	else
	{
		cout<<"Error"<<endl;
	}
	id++;
}
void arrive()
{
	string name;
	cin>>name;
	bool flag=0;
	for(int i=1;i<=q.size();i++)
	{
		if(q.front()==name)
		{
			flag=1;
			cout<<"Error"<<endl;
			break;
		}
	}
	if(flag==0)
	{
		q.push_back(name);
		cout<<"OK"<<endl;
	}
}
void leave()
{
	string name;
	cin>>name;
	bool flag=0;
	for(int i=1;i<=q.size();i++)
	{
		string x=q.front();
		q.pop_front();
		if(i<=2)
		{
			if(x==name)
			{
				cout<<"Error"<<endl;
				flag=1;
				break;
			}
			else
			{
				q.push_back(x);
			}
		}
		else
		{
			if(x!=name)
			{
				q.push_back(x);
				continue;
			}
			else
			{
				cout<<"OK"<<endl;
				flag=1;
				break;
			}
		}
	}
	if(flag==0)
	{
		cout<<"Error"<<endl;
	}
}
void input()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>s;
		switch(s[0]){
		case 'a':
			arrive();
			break;
		case 's':
			start();
			break;
		case 'l':
			leave();
			break;
		}
	}
}
int main()
{
	input();
	return 0;
}