#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],vis[N];
struct Node{int x,y,z;};vector<Node> ans;
int p1[N],p2[N],H,p3[N];
void work(){
	H=0;int i,j;
	stack<int> s1,s2;
	for(i=1;i<=n;i++) if(!vis[i]){
		if(A[i]==1) s1.emplace(i);
		else if(A[i]==2) s2.emplace(i);
		else {
			if(s1.empty()||s2.empty()) continue; 
			p1[++H]=s1.top();
			for(j=H-1;j&&p2[j]>s2.top();j--) if(p2[j]<p1[j+1]) break;
			if(p2[j]>s2.top()||s2.top()<p1[j+1]){H--;continue;}
			p2[H]=s2.top();p3[H]=i;vis[i]=vis[s1.top()]=vis[s2.top()]=1;
			s2.pop();s1.pop();
			for(j=H;j>1;j--) if(p2[j]<p2[j-1]) swap(p2[j],p2[j-1]);
		}
	}
}
void Solve(){
	int i,j;scanf("%d",&n);
	for(i=1;i<=n;i++) scanf("%d",&A[i]);
	work();for(i=1;i<=H;i++) ans.emplace_back((Node){p1[i],p2[i],p3[i]});
	reverse(vis+1,vis+n+1);reverse(A+1,A+n+1);
	work();for(i=1;i<=H;i++) ans.emplace_back((Node){n-p1[i]+1,n-p2[i]+1,n-p3[i]+1});
	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';
}