#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void solve(){
int n; cin>>n;
vector<pair<int,int>>v(n);
map<int,int>mp,pos;
vector<int>conec(2*n);
for(int i=0;i<n;i++){
int a,b; cin>>a>>b;
v[i]={a,b};
conec[a]=b;
conec[b]=a;
int x=(a+b)%(2*n);
if(x%2!=0) mp[x]++;
pos[a]=i;
pos[b]=i;
}
int maxi=0,s;
for(auto x: mp){
maxi=max(maxi,x.second);
if(maxi==x.second) s=x.first;
}
cout<<n-maxi<<"\n";
int movs=n-maxi;
if(movs==0) return;
if(maxi==0) s=2*n-1;
unordered_set<int>falta;
vector<bool>c(2*n,false);
for(int i=0;i<n;i++){
int a=v[i].first, b=v[i].second;
int x=(a+b)%(2*n);
if(x!=s){
falta.insert(a);
falta.insert(b);
}
else{
c[a]=1;
c[b]=1;
}
}
//w[i]= pin "chueco"
int act=*falta.begin();
while(movs--){
if(c[act]){
act=*falta.begin();
}
int pos1=(s-act+2*n)%(2*n);
int desde=conec[pos1];
cout<<pos[pos1]<<" "<<desde<<" "<<act<<"\n";
falta.erase(act);
falta.erase(pos1);
c[act]=1;
c[pos1]=1;
act=desde;
}
}
int main(){
ios::sync_with_stdio(0);
cout.tie(0);
cin.tie(0);
solve();
return 0;
}
