#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define int long long
#define double long double
#define ordered_set tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define S second
#define F first
#define fall(i,a,n) for(int i=a;i<=n;i++)
#define rfall(i,a,n) for(int i=a;i>=n;i--)
#define pb push_back
#define all(x) x.begin(),x.end()
#define lsb(x) (x & -x)
#define sz(x) (int)x.size()
const int MAXN=2e5+10;
const int MAXL=33;
const int inf=1e17;
const int MOD=998244353;
const int HASHBASE=146527;
const int HASHMOD=1e9+7;
typedef pair<int,int> pii;
typedef tuple<int,int,int> trio;
typedef tuple<int,int,int,int> squad;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n,a[MAXN],b[MAXN],quan[MAXN],ocp[MAXN],pl,soma[MAXN],discard[MAXN];
bool z[MAXN];
int sim(int x){
int df=x-pl; df%=(2*n); df=(df+2*n)%(2*n);
if(df<n){
int pos=pl-1-df; pos%=(2*n);pos=(pos+2*n)%(2*n);
return pos;
}
df=(2*n-df-1);
int pos=pl+df; pos%=(2*n);
return pos;
}
void dfs(int i,int x){
if(z[x]) return;
z[a[i]]=z[b[i]]=1;
int y=sim(x);
if(a[i]!=y && b[i]==x){
cout<<i<<" "<<a[i]<<" "<<y<<"\n";
dfs(ocp[y],soma[ocp[y]]-y);
}
else if(b[i]!=y && a[i]==x){
cout<<i<<" "<<b[i]<<" "<<y<<"\n";
dfs(ocp[y],soma[ocp[y]]-y);
}
}
int32_t main(){
std::ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n;
fall(i,0,n-1){
cin>>a[i]>>b[i];
if(a[i]>b[i])swap(a[i],b[i]);
ocp[a[i]]=ocp[b[i]]=i;
soma[i]=a[i]+b[i];
if(a[i] % 2 == b[i] % 2)continue;
int dist=a[i]+2*n-b[i]-1;
int au=a[i];
a[i]-=dist/2; a[i]=(a[i]%(2*n)+2*n)%(2*n);
quan[a[i]]++;
a[i]=au;
}
int ans=0;
fall(i,0,2*n)if(quan[i]>ans)ans=quan[i],pl=i;
cout<<n-ans<<"\n";
fall(i,0,2*n-1){
if(!z[i])dfs(ocp[i],i);
}
}
