#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
const int N=5e4,M=1e9;
struct BIT{
	unordered_map<int,int>tr,val;
	BIT(){tr.max_load_factor(0.8),val.max_load_factor(0.8);}
	void modi(int x,int v){if(v>val[x])for(val[x]=v;x<=M;tr[x]=max(tr[x],v),x+=x&-x);}
	int qry(int x,int v=0){while(x)v=max(v,tr[x]),x-=x&-x;return v;}
};
struct BITBIT{
	unordered_map<int,BIT>tr;
	unordered_map<int,unordered_map<int,int>>val;
	BITBIT(){tr.max_load_factor(0.8),val.max_load_factor(0.8);}
	void modi(int x,int y,int v){if(v>val[x][y])for(val[x][y]=v;x<=M;tr[x].modi(y,v),x+=x&-x);}
	int qry(int x,int y,int v=0){while(x)v=max(v,tr[x].qry(y)),x-=x&-x;return v;}
};
struct BITBITBIT{
	unordered_map<int,BITBIT>tr;
	unordered_map<int,unordered_map<int,unordered_map<int,int>>>val;
	BITBITBIT(){tr.max_load_factor(0.8),val.max_load_factor(0.8);}
	void modi(int x,int y,int z,int v){if(v>val[x][y][z])for(val[x][y][z]=v;x<=M;tr[x].modi(y,z,v),x+=x&-x);}
	int qry(int x,int y,int z,int v=0){while(x)v=max(v,tr[x].qry(y,z)),x-=x&-x;return v;}
}tr;
int n;
struct node{
	int a,b,c,d;
}v[50010];
bool cmp(const node&a,const node&b){return a.a<b.a;}
int f[50010];
int main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin>>n;
	for(int i=1;i<=n;++i)cin>>v[i].a>>v[i].b>>v[i].c>>v[i].d;
	sort(v+1,v+n+1,cmp);
	int res=0;
	for(int i=1;i<=n;++i){
		res=max(res,f[i]=tr.qry(v[i].b,v[i].c,v[i].d)+1);
		tr.modi(v[i].b,v[i].c,v[i].d,f[i]);
	}
	cout<<res<<'\n';
	return 0;
}

只过了第一个点和最后两个点，剩下的都是TLE/MLE