#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
struct Point {
ll x, y;
int idx;
};
bool operator<(Point A, Point B) {
if (A.x == B.x) return A.y < B.y;
return A.x < B.x;
}
ostream& operator<<(ostream& out, Point P) {
out << P.x << ' ' << P.y;
return out;
}
struct Seg {
Point p1, p2;
} s[100001];
ll curr_x;
bool operator<(Seg A, Seg B) {
double yA, yB;
if (A.p1.x == A.p2.x) yA = A.p1.y;
else {
double m = double(A.p2.y - A.p1.y) / (A.p2.x - A.p1.x);
double c = A.p1.y - m * A.p1.x;
yA = m * curr_x + c;
}
if (B.p1.x == B.p2.x) yB = B.p1.y;
else {
double m = double(B.p2.y - B.p1.y) / (B.p2.x - B.p1.x);
double c = B.p1.y - m * B.p1.x;
yB = m * curr_x + c;
}
return yA < yB;
}
bool operator==(Seg A, Seg B) {
return A.p1.idx == B.p1.idx;
}
Point rightmost[100001];
vector<Point> events;
set<Seg> active;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for (int i = 0; i < n; i++) {
cin >> s[i].p1.x >> s[i].p1.y >> s[i].p2.x >> s[i].p2.y;
if (s[i].p2 < s[i].p1) swap(s[i].p1, s[i].p2);
s[i].p1.idx = s[i].p2.idx = i;
events.push_back(s[i].p1);
events.push_back(s[i].p2);
}
sort(events.begin(), events.end());
Point ninf = {INT_MIN, INT_MAX, n}, inf = {INT_MAX, INT_MAX, n};
active.insert({ninf, inf}); // The "sentinel"
rightmost[n] = {0, 0, -1};
for (Point i : events) {
curr_x = i.x;
if (active.find(s[i.idx]) != active.end()) {
// Right endpoint of segment
active.erase(s[i.idx]);
auto nxt = active.lower_bound(s[i.idx]);
rightmost[nxt->p1.idx] = i;
} else {
// Left endpoint of segment
auto nxt = active.lower_bound(s[i.idx]);
if (rightmost[nxt->p1.idx].idx != -1) {
cout << rightmost[nxt->p1.idx] << ' ' << i << '\n';
}
rightmost[i.idx] = rightmost[nxt->p1.idx] = i;
active.insert(s[i.idx]);
}
}
return 0;
}
