#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long inf = 1e18 + 7;
vector<vector<int>> g;
vector<bool> used;
vector<int> pr;
bool dfs(int v){
if(used[v]){
return false;
}
used[v] = true;
for(auto u: g[v]){
if(pr[u] == -1 || dfs(pr[u])){
pr[u] = v;
pr[v] = u;
return true;
}
}
return false;
}
signed main(){
#ifdef rog
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
cin.tie(nullptr);
cout.tie(nullptr);
ios_base::sync_with_stdio(false);
int n;
cin >> n;
g.resize(n);
used.resize(n);
pr.resize(n, -1);
vector<pair<int, int>> arr(n);
for(int i = 0;i < n;i++){
cin >> arr[i].first >> arr[i].second;
}
for(int i = 0;i < n;i++){
for(int j = i + 1;j < n;j++){
if(arr[i].first == arr[j].first || arr[i].second == arr[j].second){
g[i].push_back(j);
g[j].push_back(i);
}
}
}
bool fl = true;
for(int i = 0;i < n;i++){
if(pr[i] == -1){
used = vector<bool>(n, false);
if(!dfs(i)){
fl = false;
break;
}
}
}
if(fl){
cout << "DA" << endl;
for(int i = 0;i < n;i++){
if(pr[i] > i){
cout << i + 1 << " " << pr[i] + 1 << endl;
}
}
}else{
cout << "NE" << endl;
}
return 0;
}
