#include <bits/stdc++.h>
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define debug(x) cerr << #x << " = " << (x) << ' '
#define endl cerr << '\n'
#define all(v) (v).begin(), (v).end()
#define SZ(v) (ll)(v).size()
#define lowbit(x) (x)&-(x)
#define pb emplace_back
#define F first
#define S second
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
const int N = 2e5+5;
const int MxC = 25;
bool cc[MxC][MxC][MxC], cc2[MxC][MxC];
struct Point {
ll x, y, z;
Point() {}
Point(ll xx, ll yy, ll zz) : x(xx), y(yy), z(zz) {}
} p[N];
vector<Point> v[MxC];
inline bool cmp_x(Point a, Point b) { return a.x < b.x; }
int main(void)
{ IO
ll n, i, j, tmp, ans=-1, k;
cin >> n;
for (i=1; i <= n; ++i)
cin >> p[i].x >> p[i].y >> p[i].z, cc[p[i].x][p[i].y][p[i].z] = 1;
n = 0;
for (i=1; i < MxC; ++i)
{
for (j=1; j < MxC; ++j)
{
for (k=1; k < MxC; ++k)
{
if (cc[i][j][k])
{
++n;
p[n] = {i, j, k}, v[i].pb(p[n]);
}
}
}
}
sort(p+1, p+n+1, cmp_x);
for (i=1; i <= 20; ++i)
{
for (auto cur : v[i])
{
//debug(cur.x), debug(cur.y), debug(cur.z), endl;
for (j=cur.y+1; j < MxC; ++j)
for (k=cur.z+1; k < MxC; ++k) if (cc2[j][k]) ans = max(ans, i+j+k);
}
for (auto cur : v[i])
{
for (j=1; j <= n; ++j)
{
if (p[j].x > i) break;
if ((p[j].y > cur.y && p[j].z < cur.z)
|| (p[j].y < cur.y && p[j].z > cur.z))
cc2[max(p[j].y, cur.y)][max(p[j].z, cur.z)] = 1;
}
}
}
/*for (i=1; i < MxC; ++i)
for (j=1; j < MxC; ++j) if (cc2[i][j]) debug(i), debug(j), endl;*/
cout << ans << '\n';
return 0;
}
