#include<bits/stdc++.h>
using namespace std;
namespace my_std{
	#define ll long long
	#define bl bool
	ll my_pow(ll a,ll b,ll mod){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res=(res*a)%mod;
			a=(a*a)%mod;
			b>>=1;
		}
		return res;
	}
	ll qpow(ll a,ll b){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res*=a;
			a*=a;
			b>>=1;
		}
		return res;
	}
	#define db double
	#define pf printf
	#define pc putchar
	#define fr(i,x,y) for(register ll i=(x);i<=(y);i++)
	#define pfr(i,x,y) for(register ll i=(x);i>=(y);i--)
	#define go(u) for(ll i=head[u];i;i=e[i].nxt)
	#define enter pc('\n')
	#define space pc(' ')
	#define fir first
	#define sec second
	#define MP make_pair
	#define il inline
	#define inf 8e18
	#define random(x) rand()*rand()%(x)
	#define inv(a,mod) my_pow((a),(mod-2),(mod))
	il ll read(){
		ll sum=0,f=1;
		char ch=0;
		while(!isdigit(ch)){
			if(ch=='-') f=-1;
			ch=getchar();
		}
		while(isdigit(ch)){
			sum=sum*10+(ch^48);
			ch=getchar();
		}
		return sum*f;
	}
	il void write(ll x){
		if(x<0){
			x=-x;
			pc('-');
		}
		if(x>9) write(x/10);
		pc(x%10+'0');
	}
	il void writeln(ll x){
		write(x);
		enter;
	}
	il void writesp(ll x){
		write(x);
		space;
	}
}
using namespace my_std;
set<ll> s;
ll n,a[600060],pre[600060];
queue<ll> q1,q3,q12,q32,q123,q321;
il ll find(ll x){
	set<ll>::iterator it=s.upper_bound(x);
	if(it==s.end()) return -1;
	return *it;
}
int main(){
	n=read();
	fr(i,1,n) a[i]=read();
	ll cnt1=0,cnt2=0,cnt3=0,cnt12=0,cnt32=0,cnt123=0,cnt321=0;
	fr(i,1,n){
		if(a[i]==3){
			swap(cnt1,cnt3);
			swap(cnt12,cnt32);
			swap(cnt123,cnt321);
			swap(q1,q3);
			swap(q12,q32);
			swap(q123,q321);
		}
		if(a[i]==1||a[i]==3){
			if(cnt32){
				cnt32--;
				cnt321++;
				pre[i]=q32.front();
				q32.pop();
				q321.push(i);
			}
			else if(cnt3&&cnt2&&cnt1&&find(q3.front())!=-1){
				ll pos3=q3.front(),pos2=find(pos3);
				cnt3--;
				cnt2--;
				cnt321++;
				pre[i]=pos2;
				pre[pos2]=pos3;
				q3.pop();
				s.erase(pos2);
				q321.push(i);
				if(!cnt3){
					while(!q1.empty()&&!s.empty()){
						ll tmp1=q1.front(),tmp2=find(tmp1);
						if(tmp2==-1) break;
						cnt1--;
						cnt2--;
						cnt12++;
						pre[tmp2]=tmp1;
						q1.pop();
						s.erase(tmp2);
						q12.push(tmp2);
					}
				}
			}
			else if(cnt2&&cnt123&&find(q123.front())!=-1){
				ll pos123=q123.front(),pos2=find(pos123);
				cnt123--;
				cnt2--;
				q123.pop();
				s.erase(pos2);
				cnt321++;
				cnt12++;
				q321.push(i);
				q12.push(pre[pos123]);
				pre[pos123]=0;
				pre[pos2]=pos123;
				pre[i]=pos2;
			}
			else if(cnt2&&cnt321&&find(q321.front())!=-1){
				ll pos321=q321.front(),pos2=find(pos321);
				cnt321--;
				cnt2--;
				q321.pop();
				s.erase(pos2);
				cnt321++;
				cnt12++;
				q321.push(i);
				q12.push(pos2);
				pre[i]=pre[pos321];
				pre[pos321]=0;
				pre[pos2]=pos321;
			}
			else{
				cnt1++;
				q1.push(i);
			}
		}
		if(a[i]==2){
			if(cnt1&&cnt3){
				cnt2++;
				s.insert(i);
			}
			else if(cnt1){
				cnt12++;
				cnt1--;
				pre[i]=q1.front();
				q12.push(i);
				q1.pop();
			}
			else if(cnt3){
				cnt32++;
				cnt3--;
				pre[i]=q3.front();
				q32.push(i);
				q3.pop();
			}
			else{
				cnt2++;
				s.insert(i);
			}
		}
		if(a[i]==3){
			swap(cnt1,cnt3);
			swap(cnt12,cnt32);
			swap(cnt123,cnt321);
			swap(q1,q3);
			swap(q12,q32);
			swap(q123,q321);
		}
	}
	writeln(cnt123+cnt321);
	fr(i,1,n) if(pre[i]&&pre[pre[i]]) pf("%lld %lld %lld\n",pre[pre[i]]-1,pre[i]-1,i-1);
}