#include<bits/stdc++.h>
using namespace std;
const int N=110005;
int n,tree[4*N]; 
template<class TT>inline void read(TT &xx)
{
	xx=0;char cc=getchar();bool ff=false;
	while(cc<'0'||cc>'9'){if(cc=='-')ff=true;cc=getchar();}
	while(cc>='0'&&cc<='9'){xx=(xx<<3)+(xx<<1)+cc-'0';cc=getchar();}
	if(ff)xx=-xx;
}
int x[N],y[N];
int orix[N],oriy[N],totx,toty;
int up[N],down[N],lef[N],rig[N];
struct line
{
	int type;//0表示横线，1表示竖线起点，-1表示竖线终点 
	int st,end,p;
	bool operator <(const line qwe)
	{
		if(p!=qwe.p) return p<qwe.p;
		else return type<qwe.type;
	}
}a[N];
int cnt;
#define lowbit(as) as&(-as)
void add(int x,int num){while(x<=totx+1){tree[x]+=num,x+=lowbit(x);}}
int query(int x){int sum=0; while(x>0){sum+=tree[x];x-=lowbit(x);} return sum;}
#define J 
#define F
int main()
{
	#ifdef F
	freopen("dot1.in","r",stdin);
	#endif
	read(n);
	#ifdef J
	printf("n=%d\n",n);
	#endif
	for(int i=1;i<=n;i++)
	{
		read(orix[i]);read(oriy[i]);
		x[i]=orix[i];y[i]=oriy[i];
	}
	sort(orix+1,orix+n+1);totx=unique(orix+1,orix+n+1)-orix-1;
	sort(oriy+1,oriy+n+1);toty=unique(oriy+1,oriy+n+1)-oriy-1;
	#ifdef J
	printf("totx=%d toty=%d\n",totx,toty);
	#endif
	for(int i=1;i<=n;i++)
	{
		x[i]=lower_bound(orix+1,orix+totx+1,x[i])-orix;
		y[i]=lower_bound(oriy+1,oriy+toty+1,y[i])-oriy;
	}
	memset(down,0x3f,sizeof(down));
	memset(lef,0x3f,sizeof(lef));
	memset(rig,-1,sizeof(rig));
	memset(up,-1,sizeof(up));
	for(int i=1;i<=n;i++)
	{
		up[x[i]]=max(up[x[i]],y[i]);
		down[x[i]]=min(down[x[i]],y[i]);
		lef[y[i]]=min(lef[y[i]],x[i]);
		rig[y[i]]=max(rig[y[i]],x[i]);
	}
	for(int i=1;i<=totx;i++)
	{
		#ifdef J
		printf("竖着i=%d up=%d down=%d\n",i,up[i],down[i]);
		#endif
		if(up[i]!=down[i])
		{
			a[++cnt]=(line){1,i,i,down[i]};
			a[++cnt]=(line){-1,i,i,up[i]};
		}
	}
	for(int i=1;i<=toty;i++)
	{
		#ifdef J
		printf("横着i=%d left=%d right=%d\n",i,lef[i],rig[i]);
		#endif
		if(lef[i]!=rig[i])
		{
			a[++cnt]=(line){0,lef[i],rig[i],i};
		} 
	}
	sort(a+1,a+cnt+1);
	long long ans=0; 
	for(int i=1;i<=cnt;i++)
	{
		#ifdef J
		printf("type=%d l=%d r=%d p=%d\n",a[i].type,a[i].st,a[i].end,a[i].p);
		#endif
		if(a[i].type==0) ans+=query(a[i].end-1)-query(a[i].st); 
		else add(a[i].st,a[i].type);
	}
	printf("%lld\n",ans+n);
	return 0;
}

我就是用的扫描线+是树状数组，不知道哪里错了，求助/kel