#include <stdio.h>
#include <string.h>
#define N 100000
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int xx[N * 2], yy[N * 2];
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k) {
int c = xx[ii[j]] != xx[i_] ? xx[ii[j]] - xx[i_] : yy[ii[j]] - yy[i_];
if (c == 0)
j++;
else if (c < 0) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
}
sort(ii, l, i);
l = k;
}
}
int zz[1 + N], ll[1 + N], rr[1 + N], kk[1 + N], u_, l_, r_;
int node(int k) {
static int _ = 1;
zz[_] = rand_(), kk[_] = k;
return _++;
}
long long cross2(int x1, int y1, int x2, int y2) {
return (long long) x1 * y2 - (long long) x2 * y1;
}
long long cross(int x0, int y0, int x1, int y1, int x2, int y2) {
return cross2(x1 - x0, y1 - y0, x2 - x0, y2 - y0);
}
int compare(int i, int j) {
long long c1, c2;
if (i == j)
return 0;
c1 = cross(xx[i << 1 | 0], yy[i << 1 | 0], xx[i << 1 | 1], yy[i << 1 | 1], xx[j << 1 | 0], yy[j << 1 | 0]);
c2 = cross(xx[i << 1 | 0], yy[i << 1 | 0], xx[i << 1 | 1], yy[i << 1 | 1], xx[j << 1 | 1], yy[j << 1 | 1]);
if (c1 != 0 && c2 != 0 && (c1 < 0) == (c2 < 0))
return c1 < 0 ? -1 : 1;
c1 = cross(xx[j << 1 | 0], yy[j << 1 | 0], xx[j << 1 | 1], yy[j << 1 | 1], xx[i << 1 | 0], yy[i << 1 | 0]);
return c1 > 0 ? -1 : 1;
}
void split(int u, int k) {
int c;
if (u == 0) {
u_ = l_ = r_ = 0;
return;
}
c = compare(kk[u], k);
if (c < 0) {
split(rr[u], k);
rr[u] = l_, l_ = u;
} else if (c > 0) {
split(ll[u], k);
ll[u] = r_, r_ = u;
} else {
u_ = u, l_ = ll[u], r_ = rr[u];
ll[u] = rr[u] = 0;
}
}
int merge(int u, int v) {
if (u == 0)
return v;
if (v == 0)
return u;
if (zz[u] < zz[v]) {
rr[u] = merge(rr[u], v);
return u;
} else {
ll[v] = merge(u, ll[v]);
return v;
}
}
int first(int u) { return ll[u] == 0 ? u : first(ll[u]); }
int last(int u) { return rr[u] == 0 ? u : last(rr[u]); }
int main() {
static int ii[N * 2], rep[N + 1];
int n, h, i, tmp;
scanf("%d", &n);
for (i = 0; i < n * 2; i++)
scanf("%d%d", &xx[i], &yy[i]);
for (i = 0; i < n; i++)
if (xx[i << 1 | 0] > xx[i << 1 | 1] || xx[i << 1 | 0] == xx[i << 1 | 1] && yy[i << 1 | 0] > yy[i << 1 | 1]) {
tmp = xx[i << 1 | 0], xx[i << 1 | 0] = xx[i << 1 | 1], xx[i << 1 | 1] = tmp;
tmp = yy[i << 1 | 0], yy[i << 1 | 0] = yy[i << 1 | 1], yy[i << 1 | 1] = tmp;
}
for (i = 0; i < n * 2; i++)
ii[i] = i;
sort(ii, 0, n * 2);
memset(rep, -1, (n + 1) * sizeof *rep);
for (h = 0; h < n * 2; h++) {
int i_ = ii[h];
i = i_ >> 1;
if ((i_ & 1) == 0) {
int p;
split(u_, i);
p = l_ ? kk[last(l_)] : n;
if (rep[p] != -1) {
printf("%d %d %d %d\n", xx[rep[p] << 1 | 1], yy[rep[p] << 1 | 1], xx[i_], yy[i_]);
rep[p] = -1;
}
u_ = merge(merge(l_, node(i)), r_);
} else {
int p;
split(u_, i);
p = l_ ? kk[last(l_)] : n;
if (rep[p] != -1) {
printf("%d %d %d %d\n", xx[rep[p] << 1 | 1], yy[rep[p] << 1 | 1], xx[i_], yy[i_]);
rep[p] = -1;
}
if (rep[i] != -1) {
printf("%d %d %d %d\n", xx[rep[i] << 1 | 1], yy[rep[i] << 1 | 1], xx[i_], yy[i_]);
rep[i] = -1;
}
rep[p] = i;
u_ = merge(l_, r_);
}
}
return 0;
}
