#include<bits/stdc++.h>
#define m(a,b) a=a<(b)?(b):a
using namespace std;
vector<int>G[1000];
class c{public:int x,y,z;int in(int s[]){x=*s,y=s[1],z=s[2];}};
int t[1000],s,n,i,j,x[3];c a[1000];
main()
{
	for(cin>>n;cin>>*x>>x[1]>>x[2];a[i++].in(x))sort(x,x+3);
	for(;i--;)for(j=n;j--;)if(a[j].x<a[i].x&&a[j].y<a[i].y&&a[j].z<a[i].z)G[i].push_back(j);
	for(;++i<n;m(s,t[i]+1))for(j=0;j<G[i].size();j++)m(t[i],t[j]+1);
	cout<<s<<endl;
}