#include <cstdio>
#include <cassert>
#include <cstdlib>
#include <vector>
#include <set>
#include <algorithm>
#include <queue>
#include <utility>
#define let const auto
#define rep(name,beg,end) for(auto lim_##name = end,name = beg;name <= lim_##name;name++)
#define per(name,beg,end) for(auto lim_##name = end,name = beg;name >= lim_##name;name--)
#define repn(lim) for(auto REPN_lIM = lim,REPN = 1;REPN <= REPN_lIM;REPN++)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define trace() debug("line : %d, Function : %s\n",__LINE__,__FUNCTION__)
using ci = const int;
constexpr int maxn = 1e5 + 100;
struct Seg{
#define ls (x << 1)
#define rs (x << 1 | 1)
static const int M = 100000;
std::set<int> s[maxn << 2];
void ins(ci a,ci b,ci v,ci l = 1,ci r = M,ci x = 1){
if(a <= l && b >= r){
s[x].insert(v);
return;
}
let mid = (l + r) >> 1;
if(a <= mid)ins(a,b,v,l,mid,ls);
if(b > mid)ins(a,b,v,mid + 1,r,rs);
}
bool query(ci p,ci a,ci b,ci l = 1,ci r = M,ci x = 1){
let it = s[x].lower_bound(a);
if(it != s[x].end() && *it <= b)return true;
if(l == r)return false;
let mid = (l + r) >> 1;
if(p <= mid)return query(p,a,b,l,mid,ls);
return query(p,a,b,mid + 1,r,rs);
}
#undef ls
#undef rs
};
struct Point{
int x,y;
}p[maxn];
int n;
std::vector<std::pair<int,int>> ans;
[[noreturn]] void nosol(){
std::puts("NE");
std::exit(0);
}
bool vis[maxn];
Seg seg_row,seg_col;
void match(ci a,ci b){
if(p[a].x == p[b].x){
let l = std::min(p[a].y,p[b].y);
let r = std::max(p[a].y,p[b].y);
if(seg_row.query(p[a].x,l,r))nosol();
seg_col.ins(l,r,p[a].x);
}
if(p[a].y == p[b].y){
let l = std::min(p[a].x,p[b].x);
let r = std::max(p[a].x,p[b].x);
if(seg_col.query(p[a].y,l,r))nosol();
seg_row.ins(l,r,p[a].y);
}
vis[a] = vis[b] = 1;
ans.emplace_back(a,b);
}
bool chk(ci a,ci b){
if(p[a].x == p[b].x){
let l = std::min(p[a].y,p[b].y);
let r = std::max(p[a].y,p[b].y);
if(seg_row.query(p[a].x,l,r))return false;
}
if(p[a].y == p[b].y){
let l = std::min(p[a].x,p[b].x);
let r = std::max(p[a].x,p[b].x);
if(seg_col.query(p[a].y,l,r))return false;
}
return true;
}
struct Rect{
int a,b,c,d;
};
std::vector<Rect> rect;
std::vector<int> row[maxn],col[maxn];
std::vector<int> G[maxn];
int deg[maxn];
void addedge(ci u,ci v){
G[u].push_back(v);
G[v].push_back(u);
deg[u]++;
deg[v]++;
}
void topo(){
std::queue<int> q;
rep(i,1,n)
if(!deg[i])nosol();
rep(i,1,n)
if(deg[i] == 1)q.push(i);
while(!q.empty()){
let u = q.front(); q.pop();
for(let v : G[u]){
if(vis[v])continue;
if(!vis[u])match(u,v);
if(--deg[v] == 1)q.push(v);
}
}
}
std::vector<int> stk;
void dfs(const int u){
if(vis[u])return;
vis[u] = 1;
stk.push_back(u);
for(let v : G[u])dfs(v);
}
std::vector<std::pair<std::vector<std::pair<int,int>>,std::vector<std::pair<int,int>>>> fuck;
int main(){
std::scanf("%d",&n);
rep(i,1,n)std::scanf("%d %d",&p[i].x,&p[i].y);
rep(i,1,n)
row[p[i].y].push_back(i),
col[p[i].x].push_back(i);
rep(i,0,maxn - 1)
if(row[i].size() == 2)
addedge(row[i].front(),row[i].back());
rep(i,0,maxn - 1)
if(col[i].size() == 2)
addedge(col[i].front(),col[i].back());
topo();
rep(i,1,n)
if(!vis[i]){
stk.clear();
dfs(i);
for(let s : stk)
if(!deg[s])nosol();
std::vector<std::pair<int,int>> A,B;
A.reserve(stk.size() >> 1);
B.reserve(stk.size() >> 1);
for(size_t i = 1;i < stk.size();i += 2)A.emplace_back(stk[i - 1],stk[i]);
for(size_t i = 2;i < stk.size();i += 2)B.emplace_back(stk[i - 1],stk[i]);
B.emplace_back(stk.front(),stk.back());
fuck.emplace_back(std::move(A),std::move(B));
}
std::set<int> s;
for(size_t i = 0;i < fuck.size();i++)s.insert(i);
while(!s.empty()){
bool flg = false;
for(auto it = s.begin();it != s.end();){
let i = *it;
let &pir = fuck[i];
bool fA = true,fB = true;
for(let &p : pir.first)
if(!chk(p.first,p.second)){
fA = false;
break;
}
for(let &p : pir.second)
if(!chk(p.first,p.second)){
fB = false;
break;
}
if(!fA && !fB)nosol();
if(fA && fB){
it++;
continue;
}
flg = true;
if(fA)
for(let &p : pir.first)match(p.first,p.second);
if(fB)
for(let &p : pir.second)match(p.first,p.second);
it = s.erase(it);
}
if(!flg){
let it = s.begin();
let i = *it;
let &pir = fuck[i];
for(let &p : pir.first)match(p.first,p.second);
s.erase(it);
}
}
std::puts("DA");
for(let &pir : ans)std::printf("%d %d\n",pir.first,pir.second);
assert(ans.size() == n / 2);
return 0;
}
