#include <bits/stdc++.h>
#define pb push_back
#define ff first
#define ss second
#define LLA(x) x.rbegin(),x.rend()
#define print(x) for(auto el:x)cout<<el<<' ';cout<<"\n";
#define printPII(x) for(auto [a,b]:x)cout<<a<<","<<b<<' ';cout<<'\n';
using namespace std;
using PII = pair <int, int>;
int n, k;
bool impossible;
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
cin >> n >> k;
vector <vector <int> > ans;
set <PII> bfs;
for (int i = 1; i <= n; i++) {
int x; cin >> x;
bfs.insert({x, i});
}
while(1) {
auto it = bfs.rbegin();
PII x = *it;
bfs.erase(bfs.lower_bound(x));
auto it1 = bfs.rbegin();
PII y = *it1;
bfs.erase(bfs.lower_bound(y));
if (x.ff <= 0 && y.ff <= 0) break;
ans.pb({1, x.ss, y.ss});
x.ff--, y.ff--;
if (x.ff < 0 || y.ff < 0) impossible = 1;
bfs.insert(x);
bfs.insert(y);
}
// int dbg = 0;
if (impossible) {
cout << "-1\n";
return 0;
}
cout << ans.size() << '\n';
for (auto el : ans) {
print(el);
}
}
