10pts求调，玄关

#include <cstdio>
#include <cstring>
#define int long long
using namespace std;
const int maxn=1e6+100;
struct node
{
	int dt,lp,rp;
}t[maxn];
struct hFlist
{
	int head,tail,size=0;
}ml,lt[maxn];

void init_listo()
{
	ml.head=1;
	t[1].lp=-1;
	for(int i=1;i<=1e6+9;++i)
	{
		t[i].rp=i+1;
		t[i+1].lp=i;
	}
	t[(int)(1e6+10)].rp=-1;
	ml.tail=1e6+10;
}
int get_new_nodeo()
{
	int r=ml.head;
	t[t[ml.head].rp].lp=-1;
	ml.head=t[ml.head].rp;
	t[r].rp=-1;
	t[r].lp=-1;
	return r;
}
void put_old_nodeo(int h)
{
	t[ml.tail].rp=h;
	t[h].lp=ml.tail;
	t[h].rp=-1;
	ml.tail=h;
}
void push_backo(int a,int x)
{
	int h=get_new_nodeo();
	t[h].dt=x;
	if(lt[a].size)
	{
		t[lt[a].tail].rp=h;
		t[h].lp=lt[a].tail;		
		lt[a].tail=h;
	}
	else
	{
		lt[a].head=lt[a].tail=h;
	}
	++lt[a].size;
}
void pop_backo(int a)
{
	if(lt[a].size>1)
	{
		int tt=t[lt[a].tail].lp;
		t[tt].rp=-1;		
		put_old_nodeo(lt[a].tail);
		lt[a].tail=tt;
		--lt[a].size;
	}
	else if(lt[a].size==1)
	{
		put_old_nodeo(lt[a].tail);
		lt[a].size=0;
		lt[a].head=lt[a].tail=-1;
	}
}
void push_fronto(int a,int x)
{
	int h=get_new_nodeo();
	t[h].dt=x;
	if(lt[a].size)
	{
		t[h].rp=lt[a].head;
		t[lt[a].head].lp=h;
		lt[a].head=h;
	}
	else
	{
		lt[a].head=lt[a].tail=h;
	}
	++lt[a].size;
}
void pop_fronto(int a)
{
	if(lt[a].size>1)
	{
		int tt=t[lt[a].head].lp;
		t[tt].lp=-1;
		put_old_nodeo(lt[a].head);
		lt[a].head=tt;
		--lt[a].size;
	}
	else if(lt[a].size==1)
	{
		put_old_nodeo(lt[a].head);
		lt[a].size=0;
		lt[a].head=lt[a].tail=-1;
	}
}
int sizeo(int a)
{
	return lt[a].size;
}
int fronto(int a)
{
	return t[lt[a].head].dt;
}
int backo(int a)
{
	return t[lt[a].tail].dt;
}
int q;
char s[100];
int a,x;
signed main()
{
	scanf("%lld",&q);
	init_listo();
	while(q--)
	{
		scanf("%s",s);
		if(!strcmp(s,"push_back"))
		{
			scanf("%lld%lld",&a,&x);
			push_backo(a,x);
		}
		else if(!strcmp(s,"pop_back"))
		{
			scanf("%lld",&a);
			pop_backo(a);
		}
		else if(!strcmp(s,"push_front"))
		{
			scanf("%lld%lld",&a,&x);
			push_fronto(a,x);
		}
		else if(!strcmp(s,"pop_front"))
		{
			scanf("%lld",&a);
			pop_fronto(a);
		}
		else if(!strcmp(s,"size"))
		{
			scanf("%lld",&a);
			printf("%lld\n",sizeo(a));
		}
		else if(!strcmp(s,"front"))
		{
			scanf("%lld",&a);
			if(lt[a].size)printf("%lld\n",fronto(a));
		}
		else if(!strcmp(s,"back"))
		{
			scanf("%lld",&a);
			if(lt[a].size)printf("%lld\n",backo(a));
		}
		else
		{
			printf("MEOW!!!!!\n");
		}
	}
	return 0;
}