#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define pii pair<int, int>
#define F first
#define S second
const int maxn = 5e5+10;
const int mod = 998244353;
const LL inf = 1e9;
int n, ma=-1, masum=1;
pii s[maxn];
int cnt[maxn];
int id[maxn];
int pos[maxn];
bool vis[maxn];
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n;
for(int i=0; i<n; i++){
int a, b; cin>>a>>b;
pos[a]=b;
pos[b]=a;
id[a]=id[b]=i;
cnt[(a+b)%(2*n)]++;
}
for(int i=0; i<2*n; i++){
if(i%2 and ma < cnt[i])
ma = max(ma, cnt[i]), masum=i;
}
cout<<n-ma<<"\n";
for(int i=0; i<2*n; i++){
if((i+pos[i])%(2*n) == masum) continue;
int now=i;
while(!vis[now]){
int m = (2*n+masum-now)%(2*n);
int a=now, b=pos[now], c=m, d=pos[m];
cout<<id[a]<<" "<<b<<" "<<c<<"\n";
vis[a]=1;
vis[b]=1;
now=d;
}
}
return 0;
}
