#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T> bool maximize(T &a, const T &b){ return (a < b ? a = b, 1 : 0); }
template<class T> bool minimize(T &a, const T &b){ return (a > b ? a = b, 1 : 0); }
#define fi first
#define se second
#define pb push_back
#define ii pair<int, int>
#define all(x) x.begin(), x.end()
#define TASK "nonsense"
/// end of template ///
const int N = 2e5 + 10;
struct Point
{
int x,y;
Point() {}
void input()
{
cin>>x>>y;
}
} point[N];
int n;
namespace sub1
{
bool check()
{
return (n<=400);
}
void solve()
{
int ans=0;
for(int i=1;i<=n;++i) for(int j=1;j<=n;++j) if(j!=i && point[i].x<point[j].x && point[i].y<point[j].y)
{
bool ok=0;
for(int k=1;k<=n;++k) if(k!=i && k!=j)
{
ok|=(point[i].x<point[k].x && point[k].x<point[j].x && point[i].y<point[k].y && point[k].y<point[j].y);
}
ans+=!ok;
}
cout<<ans;
}
}
void solve()
{
cin>>n;
for(int i=1;i<=n;++i) point[i].input();
if(sub1::check()) return void(sub1::solve());
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen(TASK".inp","r",stdin);
// freopen(TASK".out","w",stdout);
int testcase=1;
// cin>>testcase;
while (testcase--)
solve();
return 0;
}
