#include <stdio.h>
#include <string.h>
#define N 100000
#define M N
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int xx[N], yy[N];
int ii_[M * 2];
int compare_x(int i, int j) { return xx[i] - xx[j]; }
int compare_y(int i, int j) { return yy[i] - yy[j]; }
int compare_z(int h1, int h2) {
return yy[ii_[h1]] != yy[ii_[h2]] ? yy[ii_[h1]] - yy[ii_[h2]] : yy[ii_[h2 ^ 1]] - yy[ii_[h1 ^ 1]];
}
int (*compare)(int, int);
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 = compare(ii[j], 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 ds[(M + 1) * 2];
int find(int i) {
return ds[i] < 0 ? i : (ds[i] = find(ds[i]));
}
void join(int i, int j) {
i = find(i);
j = find(j);
if (i == j)
return;
if (ds[i] > ds[j])
ds[i] = j;
else {
if (ds[i] == ds[j])
ds[i]--;
ds[j] = i;
}
}
int zz[1 + M * 4], ll[1 + M * 4], rr[1 + M * 4], hh[1 + M * 4], u_, l_, r_;
int node(int h) {
static int _ = 1;
zz[_] = rand_();
hh[_] = h;
return _++;
}
void split(int u, int h) {
int c;
if (u == 0) {
u_ = l_ = r_ = 0;
return;
}
c = xx[ii_[hh[u] << 1 | 0]] - xx[ii_[h << 1 | 0]];
if (c < 0) {
split(rr[u], h);
rr[u] = l_, l_ = u;
} else if (c > 0) {
split(ll[u], h);
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 == 0 ? -1 : hh[u]) : first(ll[u]); }
int last(int u) { return rr[u] == 0 ? (u == 0 ? -1 : hh[u]) : last(rr[u]); }
int tr_higher(int u, int x) {
int h = -1;
while (u)
if (xx[ii_[hh[u] << 1 | 0]] > x)
h = hh[u], u = ll[u];
else
u = rr[u];
return h;
}
int main() {
static int ii[N], dd[N], cc[M + 1], hh[M * 2], qq[M];
int n, m, h, i, u1, u2;
scanf("%d", &n);
for (i = 0; i < n; i++)
scanf("%d%d", &xx[i], &yy[i]);
for (i = 0; i < n; i++)
ii[i] = i;
m = 0;
compare = compare_x, sort(ii, 0, n);
for (i = 0; i < n; i++)
if (i + 1 < n && xx[ii[i]] == xx[ii[i + 1]]) {
ii_[m << 1 | 0] = ii[i], ii_[m << 1 | 1] = ii[i + 1], m++;
dd[ii[i]]++, dd[ii[i + 1]]++;
}
compare = compare_y, sort(ii, 0, n);
for (i = 0; i < n; i++)
if (i + 1 < n && yy[ii[i]] == yy[ii[i + 1]]) {
ii_[m << 1 | 0] = ii[i], ii_[m << 1 | 1] = ii[i + 1], m++;
dd[ii[i]]++, dd[ii[i + 1]]++;
}
for (i = 0; i < n; i++)
if (dd[i] == 0) {
printf("NE\n");
return 0;
}
for (h = 0; h < m * 2; h++)
hh[h] = h;
compare = compare_z, sort(hh, 0, m * 2);
memset(ds, -1, (m + 1) * 2 * sizeof *ds);
u1 = u2 = 0;
for (h = 0; h < m * 2; h++) {
int h_ = hh[h], h1 = h_ >> 1, p, q;
if (yy[ii_[h_]] < yy[ii_[h_ ^ 1]]) {
split(u1, h1), p = last(l_), q = first(r_), u1 = merge(merge(l_, node(h1)), r_);
if (p != -1 && q != -1)
split(u2, p), u2 = merge(l_, r_);
if (p != -1)
split(u2, p), u2 = merge(merge(l_, node(p)), r_);
if (q != -1)
split(u2, h1), u2 = merge(merge(l_, node(h1)), r_);
qq[h1] = q;
if (p != -1)
qq[p] = h1;
} else if (yy[ii_[h_]] > yy[ii_[h_ ^ 1]]) {
split(u1, h1), p = last(l_), q = first(r_), u1 = merge(l_, r_);
if (p != -1)
split(u2, p), u2 = merge(l_, r_);
if (q != -1)
split(u2, h1), u2 = merge(l_, r_);
if (p != -1 && q != -1)
split(u2, p), u2 = merge(merge(l_, node(p)), r_);
if (p != -1)
qq[p] = q;
} else if (xx[ii_[h_]] < xx[ii_[h_ ^ 1]]) {
int l = xx[ii_[h_]], r = xx[ii_[h_ ^ 1]], h2, h3;
h2 = tr_higher(u1, l - 1);
if (h2 != -1 && xx[ii_[h2 << 1 | 0]] <= r) {
join(h1 << 1 | 0, h2 << 1 | 1), join(h1 << 1 | 1, h2 << 1 | 0);
while (1) {
h2 = tr_higher(u2, l - 1);
if (h2 == -1)
break;
h3 = qq[h2];
if (xx[ii_[h3 << 1 | 0]] > r)
break;
join(h2 << 1 | 0, h3 << 1 | 0), join(h2 << 1 | 1, h3 << 1 | 1);
split(u2, h2), u2 = merge(l_, r_);
}
}
}
}
for (h = 0; h < m; h++)
if (dd[ii_[h << 1 | 0]] == 1 || dd[ii_[h << 1 | 1]] == 1)
join(h << 1 | 0, m << 1 | 1), join(h << 1 | 1, m << 1 | 0);
for (h = 0; h < m; h++)
if (find(h << 1 | 0) == find(h << 1 | 1)) {
printf("NE\n");
return 0;
}
for (h = 0; h <= m; h++)
cc[h] = find(h << 1 | 0) < find(h << 1 | 1);
if (cc[m])
for (h = 0; h <= m; h++)
if (find(h << 1 | 0) == find(m << 1 | 0) || find(h << 1 | 0) == find(m << 1 | 1))
cc[h] ^= 1;
printf("DA\n");
for (h = 0; h < m; h++)
if (cc[h])
printf("%d %d\n", ii_[h << 1 | 0] + 1, ii_[h << 1 | 1] + 1);
return 0;
}
