#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i,s,e) for(int i = s; i <= (int)e; ++i)
#define DEC(i,s,e) for(int i = s; i >= (int)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define reach
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <int, int> pi;
typedef tuple<int,int,int> ti3;
typedef tuple<int,int,int,int> ti4;
int rand(int a, int b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (long long)1e18 + 500;
template <typename T> void chmax(T& a, const T b) { a=max(a,b); }
template <typename T> void chmin(T& a, const T b) { a=min(a,b); }
const int MAXN = 150005;
array<int,3>A[MAXN];
int n;
unordered_map<int,vector<int>> VX;
unordered_map<int,vector<int>> VY;
unordered_map<int,vector<int>> VZ;
set<int> sX, sY, sZ;
bool done[MAXN];
int cury, curz;
int32_t main()
{
IAMSPEED
cin >> n;
FOR(i,1,n)cin>>A[i][0]>>A[i][1]>>A[i][2];
FOR(i,1,n)sX.insert(A[i][0]);
FOR(i,1,n)sY.insert(A[i][1]);
FOR(i,1,n)sZ.insert(A[i][2]);
FOR(i,1,n){
VX[A[i][0]].pb(i);
VY[A[i][1]].pb(i);
VZ[A[i][2]].pb(i);
}
vector<int> yvals;
for(auto x:sY)yvals.pb(x); // feed all of y-values into the Y set
vector<int> zvals;
for(auto x:sZ)zvals.pb(x);// feed the z-values into the Z set
unordered_set<int> Yset, Zset;
for(auto idx:VY[yvals.back()]){
Yset.insert(idx);
}
cury=yvals.back();
yvals.pop_back();
for(auto idx:VZ[zvals.back()]){
Zset.insert(idx);
}
curz=zvals.back();
zvals.pop_back();
vector<int> xvals;
for(auto x:sX)xvals.pb(x);
reverse(all(xvals));
for(auto x_val:xvals){
db(x_val);
for(auto idx:VX[x_val]){
db(idx);
done[idx]=1;
}
bool found=0;
while(found==0){
db(found);
while(Zset.size() && Yset.size()){
int z=*Zset.begin();
int y=*Yset.begin();
if(done[z]){
Zset.erase(z);
continue;
}
if(done[y]){
Yset.erase(y);
continue;
}
if(Zset.find(y) != Zset.end()){
done[y]=1;
Yset.erase(y);
Zset.erase(y);
continue;
}
if(Yset.find(z) != Yset.end()){
done[z]=1;
Yset.erase(z);
Zset.erase(z);
continue;
}
found=1;
break;
}
if(Yset.empty()){
if(yvals.empty()){
cout<<"-1\n";exit(0);
}
cury=yvals.back();
yvals.pop_back();
for(auto idx:VY[cury]){
Yset.insert(idx);
}
}
if(Zset.empty()){
if(zvals.empty()){
cout<<"-1\n";exit(0);
}
curz=zvals.back();
zvals.pop_back();
for(auto idx:VZ[curz]){
Zset.insert(idx);
}
}
}
for(auto idx:VX[x_val]){
if(A[idx][1]<cury && A[idx][2]<curz){
db3(x_val,cury,curz);
cout<<x_val+cury+curz<<'\n';exit(0);
}
}
}
}
