懵逼了~~~

谁能帮帮我？？？

#include<bits/stdc++.h>
using namespace std;
deque<string> q;
int main(){
	int n;
	string nowplayinga="",nowplayingb="";
	cin>>n;
	while(n--){
		string cmd;
		cin>>cmd;
		if(cmd=="start"){
			if(q.empty()){
				cout<<"Error\n";
			}else{
				if(nowplayinga!=""){
					q.push_back(nowplayinga);
				}
				if(nowplayingb!=""){
					q.push_back(nowplayingb);
				}
				nowplayinga=nowplayingb="";
				cout<<q.front()<<" ";
				nowplayinga=q.front();
				q.pop_front();
				if(!q.empty()){
					cout<<q.front();
					nowplayingb=q.front();
					q.pop_front();
				}
				cout<<endl;
			}
		}else if(cmd=="arrive"){
			string x;
			cin>>x;
			if(find(q.begin(),q.end(),x)!=q.end()||nowplayinga==x||nowplayingb==x){
				cout<<"Error\n";
			}else{
				q.push_back(x);
				cout<<"OK\n";
			}
		}else{
			string x;
			cin>>x;
			deque<string>::iterator it=find(q.begin(),q.end(),x);
			if(it==q.end()){
				cout<<"Error\n";
			}else{
				q.erase(it);
				cout<<"OK\n";
			}
		}
	}
	return 0;
}

完美的三彩缤纷答案嘤嘤嘤