#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define f first
#define s second
#define endl "\n"
const int N = 5e5 + 5, mod = 1e9 + 7, inf = 1e9; //!
int t, tree[4 * N][2], cur, val[N], rr2[N][2];
pair<int,pii> p[N];
set<pii> s[4 * N][2];
void upd(int u, int id, int l,int r,int t,int val) {
if(l > id || r < id) return;
if(l == r) {
tree[u][t] = max(tree[u][t], val);
return;
}
int mid = (l + r) / 2;
upd(2 * u, id, l, mid, t, val); upd(2 * u + 1, id, mid + 1,r, t, val);
for(int k = 0; k < 2; k++) tree[u][k] = max(tree[2 * u][k], tree[2 * u + 1][k]);
}
int get(int u,int st,int en,int l,int r,int t) {
if(l > en || r < st) return 0;
if(st <= l && r <= en) return tree[u][t];
int mid = (l + r) / 2;
return max(get(2 * u, st, en, l, mid, t), get(2 * u + 1, st, en, mid + 1, r, t));
}
void updSum(int u,int id, int l,int r, int t, int val1, int val2) {
if(l > id || r < id) return;
int f = 0;
if(s[u][t].size() && s[u][t].upper_bound({val1, 0}) != s[u][t].end() ) {
if((*s[u][t].upper_bound({val1, 0})).s >= val1 + val2)f = 1;
else
if((*s[u][t].upper_bound({val1, 0})).f == val1) {
s[u][t].erase((*s[u][t].upper_bound({val1, 0})));
}
}
if(!f) s[u][t].insert({val1, val2 + val1});
while(!f && s[u][t].size() && s[u][t].upper_bound({val1 - 1, inf}) != s[u][t].begin()) {
pii p = *--s[u][t].upper_bound({val1 - 1, inf});
if(p.s > val1 + val2) break;
s[u][t].erase(p);
}
for(set<pii> :: iterator it = s[u][t].begin(); it != s[u][t].end(); it++) {
if((*it).f < val1 && (*it).s <= val1 + val2) {
s[u][t].erase(*it);
it--;
}
}
if(l == r) return;
int mid = (l + r) / 2;
updSum(2 * u, id, l, mid, t, val1, val2); updSum(2 * u + 1, id, mid + 1,r, t, val1, val2);
}
int getSum(int u,int st, int en, int l,int r,int t,int val1) {
if(l > en || r < st) return -inf;
if(st <= l && r <= en) {
if(s[u][t].upper_bound({val1 + 1, 0}) == s[u][t].end()) return -inf;
return (*s[u][t].upper_bound({val1 + 1, 0})).s;
}
int mid = (l + r) / 2;
return max(getSum(2 * u, st, en, l, mid, t, val1), getSum(2 * u + 1, st, en, mid + 1, r, t, val1));
}
void add(pair<int, pii> p) {
int a = p.s.f, b = p.s.s;
int mxa = get(1, 1, a - 1, 1, cur, 0);
int mxb = get(1, 1, b - 1, 1, cur, 1);
upd(1, a, 1, cur, 0, b);
upd(1, b, 1, cur, 1, a);
if(mxa <= b) mxa = 0; if(mxb <= a) mxb = 0;
// rr2[a][0] = max(rr2[a][0], mxa);
// rr2[b][1] = max(rr2[b][1], mxb);
if(mxa)
updSum(1, a, 1, cur, 0, val[mxa], val[a]);
if(mxb)
updSum(1, b, 1, cur, 1, val[mxb], val[b]);
}
int getSum2(int u,int st, int en, int l,int r,int t,int val1) {
int ans = -inf;
for(int i = st; i <= en; i++) {
if(val1 < val[rr2[i][t]])
ans = max(ans, val[rr2[i][t]] + val[i]);
}
return ans;
}
main() {
ios_base::sync_with_stdio(false),
cin.tie(0),cout.tie(0);
int n;
cin >> n;
vector<int> x;
map<int,int> id;
for(int i = 1; i <= n; i++) {
cin >> p[i].f >> p[i].s.f >> p[i].s.s;
x.push_back(p[i].f); x.push_back(p[i].s.f); x.push_back(p[i].s.s);
}
sort(x.begin(),x.end());
cur = 0;
for(int i = 0; i < x.size(); i++) {
if(!i || x[i] != x[i - 1]) ++cur;
id[x[i]] = cur;
val[cur] = x[i];
}
for(int i = 1; i <= n; i++) {
p[i].f = id[p[i].f];
p[i].s.f = id[p[i].s.f];
p[i].s.s = id[p[i].s.s];
}
val[0] = -inf;
sort(p + 1, p + n + 1);
int last = 0, ans = -inf;
for(int i = 1; i <= n; i++) {
int x = 0;
x = max(getSum(1, p[i].s.s + 1, cur, 1, cur, 1, val[p[i].s.f]), getSum(1, p[i].s.f + 1, cur, 1, cur, 0, val[p[i].s.s]));
ans = max(ans, x + val[p[i].f]);
if(p[i].f != p[i + 1].f) {
for(int j = last + 1; j <= i; j++) {
add(p[j]);
}
last = i;
}
}
ans = max(ans, -1);
cout << ans;
}
