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

int no(){
    cout << "-1";
    return 0;
}

int main() {
    set<pair<int, int>> st;
    int n;
    cin >> n;
    int sum = 0;
    for(int i = 1; i <= n; i++){
        int x;
        cin >> x;
        st.insert({x, i});
    }

    vector<pair<int, int>> vec;

    while(!st.empty()){
        auto ele = *st.begin();
        st.erase(st.begin());
        if(ele.first == 1){
            if(st.empty())return no();
            auto it = st.lower_bound({3, 0});

            while(it != st.end() && it->first&1)it++;

            if(it == st.end())it = st.lower_bound({2, 0});
            if(it == st.end()){
                if(st.size() >= 2)return no();
                vec.push_back({ele.second, st.begin()->second});
                break;
            }
            auto nw = *it;
            st.erase(it);
            nw.first--;
            vec.push_back({nw.second, ele.second});
            st.insert(nw);
        } 
        else if(ele.first == 2){
            if(st.size() < 2 || st.begin()->first != 2)return no();
            auto it = st.lower_bound({4, 0});
            if(it == st.end())it = st.lower_bound({3, 0});
            if(it == st.end()){
                if(st.size() < 2)return no();
                int prv = ele.second;
                for(auto v: st){
                    vec.push_back({prv, v.second});
                    prv = v.second;
                }
                vec.push_back({prv, ele.second});
                break;
            }
            else {
                auto nxt = *st.begin();
                st.erase(st.begin());
                vec.push_back({nxt.second, ele.second});
                vec.push_back({nxt.second, it->second});
                vec.push_back({ele.second, it->second});
                auto nw = *it;
                nw.first -= 2;
                st.erase(it);
                st.insert(nw);
            }
        }
        else return no();
    }
    cout << vec.size() << "\n";
    for(auto v: vec)cout << "2 " << v.first << " " << v.second << "\n";
}