#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

struct node {
	ll x, y, z;
	bool friend operator < (node xx, node yy) {
		return xx.z > yy.z;
	}
} st1, st2;

ll n, ans, s1, s3;
ll a[500100];
ll t[10];
ll s[5][500100];
ll p[5][500100];
ll pos[10];
priority_queue<node> q;

int main() {
//	freopen("count.in", "r", stdin);
//	freopen("count.out", "w", stdout);
	scanf("%lld", &n);
	for (ll i = 1; i <= n; i++) {
		scanf("%lld", &a[i]);
		s[a[i]][++t[a[i]]] = i;
	}
	pos[1] = pos[3] = 1;
	for (ll i = 1; i <= t[2]; i++) {
		ll x = s[2][i];
		while (pos[1] <= t[1] && s[1][pos[1]] <= x) {
			p[1][++s1] = s[1][pos[1]];
			pos[1]++;
		}
		while (pos[3] <= t[3] && s[3][pos[3]] <= x) {
			p[3][++s3] = s[3][pos[3]];
			pos[3]++;
		}
		if (s1 && pos[3] <= t[3] && !(s1 && pos[3] <= t[3] && s3 && pos[1] <= t[1] && s[3][pos[3]] > s[1][pos[1]])) {
			ans++;
			st1.x = p[1][s1];
			st1.y = x;
			st1.z = s[3][pos[3]];
			s1--;
			pos[3]++;
			q.push(st1);
			continue;
		}
		if (s3 && pos[1] <= t[1]) {
			ans++;
			st1.x = p[3][s3];
			st1.y = x;
			st1.z = s[1][pos[1]];
			s3--;
			pos[1]++;
			q.push(st1);
			continue;
		}
		if (ans && pos[1] < t[1] && pos[3] < t[3]) {
			st1 = q.top();
			if (st1.z <= x) {
				q.pop();
				if (a[st1.x] == 3) {
					ans++;
					st2.x = st1.z;
					st2.y = x;
					st2.z = s[3][pos[3]];
					st1.z = s[1][pos[1]];
				} else {
					ans++;
					st2.x = st1.z;
					st2.y = x;
					st2.z = s[1][pos[1]];
					st1.z = s[3][pos[3]];
				}
				q.push(st1);
				q.push(st2);
				pos[1]++;
				pos[3]++;
				continue;
			}
		}
		//~ cout << i << " " << s1 << " " << s3 << " " << pos[1] << " " << pos[3] << endl;
	}
	//~ cout << t[2] << endl;
	//~ cout << t[1] << " " << t[3] << endl;
	printf("%lld\n", ans);
	while (!q.empty()) {
		st1 = q.top();
		q.pop();
		printf("%lld %lld %lld\n", st1.x - 1, st1.y - 1, st1.z - 1);
	}
	//~ for (ll i = 1; i <= ans; i++) {
		//~ printf("%lld %lld %lld\n", d[i].x - 1, d[i].y - 1, d[i].z - 1);
	//~ }
	return 0;
}