# include <bits/stdc++.h>
# define ep emplace_back
# define pb pop_back
# define sz(x) x.size()

# define v(y,x) std::get<(x)>(y)
	

const int N=600010,INF=0x3f3f3f3f;

inline int read(void){
	int res,f=1;
	char c;
	while((c=getchar())<'0'||c>'9')
		if(c=='-')f=-1;
	res=c-48;
	while((c=getchar())>='0'&&c<='9')
		res=res*10+c-48;
	return res*f;
}


int main(void){
	std::vector <std::tuple <int> > v0,v2;
	std::vector <std::tuple <int,int> > v01,v21;
	std::vector <std::tuple <int,int,int> > v012,v210,v021;
	std::vector <std::tuple <int,int,int,int> > v0121,v2101;

	int n=read();
	
	for(int i=1;i<=n;++i){
		int x=read()-1;
		if(x==0){
			if(sz(v21)){
				auto c=v21.back();
				v210.emplace_back(v(c,0),v(c,1),i);
				v21.pb();
			}else if(sz(v021)){
				auto c=v021.back();
				v210.ep(v(c,1),v(c,2),i);
				v0.ep(v(c,0));
				v021.pb();
			}else if(sz(v0121)){
				auto c=v0121.back();
				v210.ep(v(c,2),v(c,3),i);
				v01.ep(v(c,0),v(c,1));
				v0121.pb();
			}else if(sz(v2101)){
				auto c=v2101.back();
				v210.ep(v(c,0),v(c,1),i);
				v01.ep(v(c,2),v(c,3));
				v2101.pb();
			}else v0.ep(i);
			
		}else if(x==1){
			if(sz(v0)&&sz(v2)){
				auto c0=v0.back(),c2=v2.back();
				v021.ep(v(c0,0),v(c2,0),i);
				v0.pb(),v2.pb();
			}else if(sz(v0)){
				auto c=v0.back();
				v01.ep(v(c,0),i);
				v0.pb();
			}else if(sz(v2)){
				auto c=v2.back();
				v21.ep(v(c,0),i);
				v2.pb();
			}else if(sz(v021)){
				auto c=v021.back();
				v01.ep(v(c,0),v(c,2));
				v21.ep(v(c,1),i);
				v021.pb();
			}else if(sz(v012)){
				auto c=v012.back();
				v0121.ep(v(c,0),v(c,1),v(c,2),i);
				v012.pb();
			}else if(sz(v210)){
				auto c=v210.back();
				v2101.ep(v(c,0),v(c,1),v(c,2),i);
				v210.ep();
			}
		}else{
			if(sz(v01)){
				auto c=v01.back();
				v012.emplace_back(v(c,0),v(c,1),i);
				v01.pb();
			}else if(sz(v021)){
				auto c=v021.back();
				v012.ep(v(c,0),v(c,2),i);
				v2.ep(v(c,1));
				v021.pb();
			}else if(sz(v2101)){
				auto c=v2101.back();
				v012.ep(v(c,2),v(c,3),i);
				v21.ep(v(c,0),v(c,1));
				v2101.pb();
			}else if(sz(v0121)){
				auto c=v0121.back();
				v012.ep(v(c,0),v(c,1),i);
				v21.ep(v(c,2),v(c,3));
				v0121.pb();
			}else v2.ep(i);	
		}
	}
	
	printf("%d\n",(int)(v012.size()+v210.size()+v0121.size()+v2101.size()));
	
	for(auto w:v012) printf("%d %d %d\n",v(w,0),v(w,1),v(w,2));
	for(auto w:v210) printf("%d %d %d\n",v(w,0),v(w,1),v(w,2));	
	for(auto w:v0121) printf("%d %d %d\n",v(w,0),v(w,1),v(w,2));	
	for(auto w:v2101) printf("%d %d %d\n",v(w,0),v(w,1),v(w,2));
	
	return 0;
}