#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define PRINT cout << "HERE" << endl
const int INF = 1e9+7;
int N, P;
vector<int> took, done;
vector<vector<pair<int,int>>> rot;
vector<pair<pair<int,int>, int>> str;
vector<int> atpin;
signed main() {
cin.tie(0); ios::sync_with_stdio(false);
cin >> N;
P = 2*N;
rot.resize(P), took.resize(P), done.resize(N), str.resize(N), atpin.resize(P);
for(int i = 0; i < N; i++) {
int a, b;
cin >> a >> b;
rot[(a+b)%P].push_back({a, b});
str[i] = {{a, b}, (a+b)%P};
atpin[a] = atpin[b] = i;
}
pair<int,int> bsf = {0, 0};
for(int i = 0; i < P; i++) {
if (i % 2) {
bsf = max(bsf, make_pair((int)rot[i].size(), i));
}
}
int r = bsf.second;
priority_queue<pair<int,int>> todo;
for(int i = 0; i < N; i++) {
if (str[i].second == r) {
took[str[i].first.first] = took[str[i].first.second] = 1;
done[i] = 1;
}
else todo.push({0, i});
}
int res = 0;
vector<vector<int>> res2;
while(todo.size()) {
int i = todo.top().second;
todo.pop();
if (i == -1 || done[i]) continue;
done[i] = 1;
auto [a, b] = str[i].first;
res++;
if (!took[a]) {
took[a] = 1;
took[(r-a+P)%P] = 1;
atpin[b] = -1;
todo.push({1, atpin[(r-a+P)%P]});
res2.push_back({i, b, (r-a+P)%P});
} else {
took[b] = 1;
took[(r-b+P)%P] = 1;
atpin[a] = -1;
todo.push({1, atpin[(r-b+P)%P]});
res2.push_back({i, a, (r-b+P)%P});
}
}
cout << res << endl;
for(int i = 0; i < res; i++) {
cout << res2[i][0] << ' ' << res2[i][1] << ' ' << res2[i][2] << endl;
}
}
