#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main()
{
    int n;
    cin >> n;
    vector<int> arr1, arr2, arr3;
    for (int i = 1; i <= n; i++){
        int a; cin >> a;
        if (a == 1) arr1.push_back(i);
        else if (a == 2) arr2.push_back(i);
        else arr3.push_back(i);
    }
    int mx = min({arr1.size(), arr2.size(), arr3.size()});
    cout << mx << endl;
    for (int i = 0; i < mx; i++){
        cout << arr1[i] << ' ' << arr2[i] << ' ' << arr3[i] << endl;
    }
}