#include <algorithm>
#include <cmath>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <deque>
#include <map>
#include <chrono>
#include <random>
#include <bitset>
#include <tuple>
#define SZ(x) int(x.size())
#define FR(i,a,b) for(int i=(a);i<(b);++i)
#define FOR(i,n) FR(i,0,n)
#define FAST ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define A first
#define B second
#define mp(a,b) make_pair(a,b)
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef unsigned __int128 U128;
typedef __int128 I128;
typedef std::pair<int,int> PII;
typedef std::pair<LL,LL> PLL;
using namespace std;
const LL MAXN=2e5+5;
LL p[MAXN][2], v[MAXN], at[MAXN];
bool good[MAXN];
signed main(){
FAST;
LL n; cin>>n;
FOR(i,n){
LL a,b; cin>>a>>b;
p[i][0]=a;
p[i][1]=b;
at[a]=at[b]=i;
v[(a+b)%(2*n)]++;
}
LL mx=0, id=0;
for (int i=1; i<2*n; i+=2){
if (v[i]>=mx){
mx=v[i];
id=i;
}
}
cout<<n-mx<<"\n";
vector<pair<LL,PLL> > q;
FOR(i,n){
LL a=p[i][0], b=p[i][1];
if ((a+b)%(2*n)!=id) q.push_back(mp(i, mp(a,b)));
else good[a]=good[b]=true;
}
FOR(j,SZ(q)){
LL i=q[j].A, a=q[j].B.A, b=q[j].B.B;
if (good[a] || good[b]) continue;
LL c=(2*n+id-a)%(2*n);
while (at[c]!=-1){
cout<<i<<" "<<b<<" "<<c<<"\n";
at[b]=-1;
good[a]=good[c]=true;
LL nxt=at[c], na=p[nxt][0], nc=p[nxt][1];
if (na==c) swap(na,nc);
b=c;
a=na;
c=(2*n+id-a)%(2*n);
i=nxt;
}
cout<<i<<" "<<b<<" "<<c<<"\n";
good[a]=good[c]=true;
}
return 0;
}
