#include <bits/stdc++.h>
using namespace std;
#define ll long long
struct node{
int a, b;
ll val;
};
int main() {
int n, k;
cin>>n>>k;
pair<ll, int> a[n];
bool bl=false;
for(int i=0; i<n; i++){
cin>>a[i].first;
a[i].second=i+1;
if(i>0 && a[i]!=a[i-1]){
bl=true;
}
}
if(bl){
int g;
for(int i=1; i<=k; i++){
if(n%i==0 && k%i==0){
g=i;
}
}
if((n*a[0].first)%k!=0){
cout<<-1;
return 0;
}
cout<<n/g<<'\n';
for(int i=0; i<n/g; i++){
cout<<a[0].first*g/k<<" ";
for(int j=0; j<k; j++){
cout<<(i*g+j)%n+1LL<<" ";
}
cout<<'\n';
}
return 0;
}
if(n==2){
if(a[0].first==a[1].first){
cout<<a[0].first<<" "<<1<<" "<<2<<'\n';
}else{
cout<<-1<<'\n';
}
return 0;
}
sort(a, a+n, [&](pair<ll, int> x, pair<ll, int> y){
return x.first<y.first;
});
int sum=0;
for(int i=0; i<n-1; i++){
sum+=a[i].first;
}
if(sum<a[n-1].first || (sum+a[n-1].first)%2==1){
cout<<-1;
}else{
sum-=a[n-1].first;
vector<node> v;
while(sum>0){
if(sum>=2*a[n-3].first){
sum-=2*a[n-3].first;
v.push_back({a[n-2].second, a[n-3].second, a[n-3].first});
a[n-2].first-=a[n-3].first;
a[n-3].first=0;
}else{
v.push_back({a[n-2].second, a[n-3].second, sum/2});
a[n-2].first-=sum/2;
a[n-3].first-=sum/2;
break;
}
for(int i=n-3; i>0; i--){
swap(a[i], a[i-1]);
}
for(int i=n-2; i>0; i--){
if(a[i].first>=a[i-1].first){
break;
}
swap(a[i], a[i-1]);
}
}
for(int i=0; i<n-1; i++){
if(a[i].first>0){
v.push_back({a[n-1].second, a[i].second, a[i].first});
}
}
cout<<v.size()<<'\n';
for(auto& it : v){
cout<<it.val<<" "<<it.a<<" "<<it.b<<'\n';
}
}
}
