#include <bits/stdc++.h>
using namespace std;
#define file "test"
#define ll long long
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define all(v) (v).begin(), (v).end()
const int N=1e5+2, INF=1e6;
int n,a[N],b[N],c[N],d[N],bit[INF+2],res,f[N];
vector<int> v;
struct hihi
{
int x,y,id;
bool operator < (const hihi &o) const
{
if (x!=o.x) return x < o.x; else return id > o.id;
}
};
vector<hihi> event;
void update(int x, int val)
{
for (; x<=INF; x+=x&-x) bit[x]=max(bit[x], val);
}
int get(int x)
{
int res=0; for (; x>0; x-=x&-x) res=max(res, bit[x]);
return res;
}
int main()
{
//freopen(file".inp", "r", stdin);
//freopen(file".out", "w", stdout);
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n;
for (int i=1;i<=n;i++)
{
cin>>a[i]>>b[i]>>c[i]>>d[i];
v.pb(a[i]); v.pb(b[i]); v.pb(c[i]); v.pb(d[i]);
}
for (int i=1;i<=n;i++)
{
a[i] = lower_bound(all(v), a[i]) - v.begin()+1;
b[i] = lower_bound(all(v), b[i]) - v.begin()+1;
c[i] = lower_bound(all(v), c[i]) - v.begin()+1;
d[i] = lower_bound(all(v), d[i]) - v.begin()+1;
event.pb({a[i], c[i], i});
event.pb({b[i], d[i], -i});
}
sort(all(event));
for (hihi e : event)
{
int x=e.x, y=e.y;
if (e.id > 0)
{
f[e.id] = get(y-1) + 1;
res=max(res, f[e.id]);
}
else update(y, f[-e.id]);
}
cout<<res;
}
