#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vl vector<ll>
#define ff(aa, bb, cc) for(ll aa = bb; aa < cc; aa++)
#define pb push_back
#define all(aaa) aaa.begin(), aaa.end()
#define rall(aaa) aaa.rbegin(), aaa.rend()
#define pll pair<ll, ll>
#define fi first
#define se second
#define vb vector<bool>
#define ed "\n"
#define vs vector<string>
int main(){
ll n;
cin >> n;
ll m = 2*n;
vl a(n), b(n), par(m), str(m);
unordered_map<ll, vl> odd;
ff(i, 0, n){
cin >> a[i] >> b[i];
par[a[i]] = b[i];
par[b[i]] = a[i];
str[a[i]] = i;
str[b[i]] = i;
ll s = (a[i]+b[i])%m;
if(s % 2 != 0){
odd[s].pb(i);
}
}
ll sz = 0, best = 1;
for(auto &x : odd){
if(x.se.size() > sz){
sz = x.se.size();
best = x.fi;
}
}
vb isok(n, false);
if(odd[best].size() > 0){
for(auto &x : odd[best]){
isok[x] = true;
}
}
vl keep(n, -1);
vb vis(m, false);
ff(i, 0, m){
if(isok[str[i]] || vis[i]) continue;
ll p = i;
while(!vis[p]){
vis[p] = true;
keep[str[p]] = p;
ll q = par[p];
vis[q] = true;
p = (best-q)%m;
if(p < 0) p += m;
}
}
cout << n-sz << ed;
ff(i, 0, n){
if(isok[i]) continue;
ll k = keep[i];
ll d = (best-k)%m;
if(d < 0) d += m;
cout << i << ' ' << par[k] << ' ' << d << ed;
}
}
