#include<bits/stdc++.h>
#define Gc() getchar() 
#define Me(x,y) memset(x,y,sizeof(x))
#define Mc(x,y) memcpy(x,y,sizeof(x))
#define d(x,y) ((m)*(x-1)+(y))
#define R(n) (rnd()%(n)+1)
#define Pc(x) putchar(x)
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
using namespace std;using ll=long long;using db=double;using lb=long db;using ui=unsigned;using ull=unsigned long long;using pii=pair<int,int>;using LL=__int128;
const int N=6e5+5,M=N*4,K=600+5,mod=998244353,Mod=mod-1;const db eps=1e-6;const ll INF=1e18+7;mt19937 rnd(263082);
int n,A[N];
vector<int> S[N];
struct Node{int x,y,z;};vector<Node> ans; 
void Solve(){
	int i,j;scanf("%d",&n);
	deque<int> s1,s3;
	for(i=1;i<=n;i++) scanf("%d",&A[i]);
	for(i=1;i<=n;i++) {
		if(A[i]==1) s1.emplace_back(i);
		if(A[i]==3) s3.emplace_back(i);
	}
	vector<int> p1,p2,q1,q2;
	while(!s1.empty()&&!s3.empty()){
		if(s1.front()<s3.front()) p1.emplace_back(s1.front()),p2.emplace_back(s3.back()),s1.pop_front(),s3.pop_back();
		else q1.emplace_back(s1.back()),q2.emplace_back(s3.front()),s1.pop_back(),s3.pop_front();
	}
	sort(p1.begin(),p1.end());sort(p2.begin(),p2.end());for(i=0;i<p1.size();i++) S[p1[i]].emplace_back(p2[i]);
	sort(q1.begin(),q1.end());sort(q2.begin(),q2.end());for(i=0;i<q1.size();i++) S[q2[i]].emplace_back(q1[i]);
	priority_queue<pii> q;
	for(i=1;i<=n;i++){
		for(int j:S[i]) q.emplace(-j,i);
		if(A[i]==2){
			while(!q.empty()&&-q.top().fi<i) q.pop();
			if(!q.empty()) ans.emplace_back((Node){q.top().se,i,-q.top().fi}),q.pop();
		}
	}
	printf("%d\n",ans.size());
	for(auto i:ans) printf("%d %d %d\n",i.x-1,i.y-1,i.z-1);
}
int main(){
	int t=1;
	// scanf("%d",&t);
	while(t--) Solve();
	cerr<<clock()*1.0/CLOCKS_PER_SEC<<'\n';
}