490A

#include<bits/stdc++.h>
#define lli long long int
#define vi vector<int>
#define vlli vector<lli>
#define pii pair<int,int>
#define vpi vector<pii>
#define mp unordered_map<char,int>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define ff first
#define ss second
 
#define MOD1 1000000007
#define MOD2 1000000009
using namespace std;
signed main(){
  int n,a;cin>>n;
  vector<int> v1,v2,v3;
  for (int i=1;i<=n;i++){
    cin>>a;
    if (a==1){ v1.emplace_back(i);}
    else if (a==2){ v2.emplace_back(i);}
    else {v3.emplace_back(i);}}
    int mini= min(min(v1.size(),v2.size()),v3.size());
    cout<<mini<<"\n";
    for (int i=0; i<mini;i++){
      cout<<v1[i]<<" "<<v2[i]<<" "<<v3[i]<<"\n";
    }
    return 0;
}