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

#define x first
#define y second
// #define int long long
#define mp(x, y) make_pair(x, y)
#define eb(...) emplace_back(__VA_ARGS__)
#define fro(i, x, y) for(int i = (x); i <= (y); i++)
#define pre(i, x, y) for(int i = (x); i >= (y); i--)
inline void JYFILE19();

typedef long long i64;
typedef pair<int, int> PII;

bool ST;
const int N = 1e6 + 10;
const int mod = 998244353;

int n, m, a[N], b[N], vs[N], ds[N], pr[N], sf[N];
queue<int> n1;
queue<PII> n2;
queue<tuple<int, int, int>> n3;

signed main() {
	JYFILE19();
	cin >> n;
	fro(i, 1, n) {
		cin >> a[i], b[i] = a[i];
	}
	int it = n;
	fro(i, 1, n) {
		if(a[i] == 3) {
			while(it > i && a[it] != 1) {
				it--;
			}
			if(i == it) break;
			swap(a[it], a[i]);
			vs[i] = vs[it] = 1;
		}
	}
	fro(i, 1, n) {
		if(a[i] == 1) {
			n1.emplace(i);
		}
		if(a[i] == 2) {
			if(n1.size()) {
				n2.emplace(n1.front(), i);
				n1.pop();
			}
		}
		if(a[i] == 3) {
			if(n2.size()) {
				n3.emplace(n2.front().x, n2.front().y, i);
				n2.pop();
			}
		}
	}
	cout << n3.size() << "\n";
	vector<tuple<int, int, int>> num1, num2;
	while(n3.empty() == 0) {
		int x, y, z;
		tie(x, y, z) = n3.front(); n3.pop();
		if((vs[x] ^ vs[z]) == 0) {
			cout << x - 1 << " " << y - 1 << " " << z - 1 << "\n";
			ds[x] = ds[y] = ds[z] = 1;
		}
		else {
			int id = b[x], ax, ay, az;
			if(vs[x] == 0) id = a[x];
			if(vs[z] == 0) id = a[z];
			if(id == 1) {
				if(num2.empty()) {
					num1.eb(x, y, z);
					goto ed;
				}
				else {
					tie(ax, ay, az) = num2.back();
					num2.pop_back();
				}
			}
			else {
				if(num1.empty()) {
					num2.eb(x, y, z);
					goto ed;
				}
				else {
					tie(ax, ay, az) = num1.back();
					num1.pop_back();
				}
			}
			if(x < ay) {
				cout << ax - 1 << " " << y - 1 << " " << z - 1 << "\n";
				cout << x - 1 << " " << ay - 1 << " " << az - 1 << "\n";
			}
			else {
				if(az < y) {
					cout << ax - 1 << " " << ay - 1 << " " << x - 1 << "\n";
					cout << az - 1 << " " << y - 1 << " " << z - 1 << "\n";
				}
				else {
					cout << ax - 1 << " " << ay - 1 << " " << z - 1 << "\n";
					cout << x - 1 << " " << y - 1 << " " << az - 1 << "\n";
				}
			}
			ds[ax] = ds[ay] = ds[az] = ds[x] = ds[y] = ds[z] = 1;
			ed:;
		}
	}
	int id;
	if(num1.size()) {
		id = 3;
		for(auto i : num1) {
			int x, y, z;
			tie(x, y, z) = i;
			ds[y] = 2, pr[y] = x, sf[y] = z;
		}
	}
	if(num2.size()) {
		id = 1;
		for(auto i : num2) {
			int x, y, z;
			tie(x, y, z) = i;
			ds[y] = 2, pr[y] = x, sf[y] = z;
		}
	}
	queue<PII> q;
	fro(i, 1, n) {
		if(b[i] == id && !ds[i]) {
			if(q.empty() || q.front().y == 1) {
				q.emplace(i, 1);
			}
			else if(!q.empty()) {
				int x = q.front().x;
				cout << pr[x] - 1 << " " << x - 1 << " " << i - 1 << "\n";
				q.pop();
			}
		}
		if(ds[i] == 2) {
			if(q.empty() || q.front().y == 2) {
				q.emplace(i, 2);
			}
			else if(!q.empty()) {
				int x = q.front().x;
				cout << x - 1 << " " << i - 1 << " " << sf[i] - 1 << "\n";
				q.pop();
			}
		}
	}
	return 0;
}

bool ED;
inline void JYFILE19() {
	// freopen("", "r", stdin);
	// freopen("", "w", stdout);
	ios::sync_with_stdio(0), cin.tie(0);
	double MIB = fabs((&ED-&ST)/1048576.), LIM = 32;
	cerr << "MEMORY: " << MIB << endl, assert(MIB<=LIM);
}