#include<bits/stdc++.h>
#define int long long
using namespace std;
int inf=1e18;
struct point{
int id,x,y;
point(int _id=0,int _x=0,int _y=0){
id=_id,x=_x,y=_y;
}
friend bool operator<(point a,point b){
return a.x>b.x;
}
};
int val[200005];
struct segtree{
struct node{
int mn,mn2,mx,mx2,fmn,fmx;
node(int _mn=inf,int _mn2=inf,int _mx=-inf,int _mx2=-inf,int _fmn=1,int _fmx=1){
mn=_mn,mn2=_mn2,mx=_mx,mx2=_mx2,fmn=_fmn,fmx=_fmx;
}
friend node operator+(node a,node b){
node c;
c.mn=min(a.mn,b.mn);
c.mx=max(a.mx,b.mx);
c.fmn=(a.mn==b.mn?a.fmn+b.fmn:(a.mn<b.mn?a.fmn:b.fmn));
c.fmx=(a.mx==b.mx?a.fmx+b.fmx:(a.mx>b.mx?a.fmx:b.fmx));
c.mn2=(a.mn==b.mn?min(a.mn2,b.mn2):(a.mn<b.mn?min(a.mn2,b.mn):min(a.mn,b.mn2)));
c.mx2=(a.mx==b.mx?max(a.mx2,b.mx2):(a.mx>b.mx?max(a.mx2,b.mx):max(a.mx,b.mx2)));
return c;
}
};
node info[800005];
int ch[800005];
void push(int st,int en,int i){
if(!ch[i])return;
if(ch[i]<=info[i].mn)return;
info[i].mn=ch[i];
if(ch[i]>info[i].mx)info[i].mx=ch[i],info[i].mx2=-inf;
else if(ch[i]>info[i].mx2)info[i].mx2=ch[i];
if(st!=en){
ch[i*2]=max(ch[i],ch[i*2]);
ch[i*2+1]=max(ch[i],ch[i*2+1]);
}
ch[i]=0;
}
void build(int st,int en,int i){
if(st==en)return void(info[i]=node(inf,inf,inf,-inf));
int m=(st+en)/2;
build(st,m,i*2);
build(m+1,en,i*2+1);
info[i]=info[i*2]+info[i*2+1];
}
int chmax(int st,int en,int i,int l,int r,int val){
push(st,en,i);
if(st>r||en<l||val<=info[i].mn)return 0;
if(st>=l&&en<=r&&val<info[i].mn2){
//cerr<<st<<" "<<en<<" "<<info[i].mn<<" "<<info[i].mn2<<":"<<val<<"\n";
ch[i]=val;
push(st,en,i);
return info[i].fmn;
}
int m=(st+en)/2;
int tans=chmax(st,m,i*2,l,r,val)+chmax(m+1,en,i*2+1,l,r,val);
info[i]=info[i*2]+info[i*2+1];
return tans;
}
void upd(int st,int en,int i,int pos,int val){
push(st,en,i);
if(st>pos||en<pos)return;
if(st==en)return void(info[i]=node(val,inf,val,-inf));
int m=(st+en)/2;
upd(st,m,i*2,pos,val);
upd(m+1,en,i*2+1,pos,val);
info[i]=info[i*2]+info[i*2+1];
}
}tr;
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;cin>>n;
vector<point>p;
vector<int>y;
for(int i=0;i<n;i++){
int a,b;cin>>a>>b;
p.push_back(point(i,a+1,b+1));
y.push_back(b+1);
}
sort(p.begin(),p.end());
sort(y.begin(),y.end());
int ans=0;
tr.build(1,n,1);
for(int i=0;i<p.size();i++){
int id=lower_bound(y.begin(),y.end(),p[i].y)-y.begin()+1;
//cerr<<"chmax:\n";
ans+=tr.chmax(1,n,1,id+1,n,id);
//cerr<<p[i].id<<" "<<ans<<" "<<id<<"\n";
tr.upd(1,n,1,id,0);
}
cout<<ans;
}
