#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
#define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
inline bool isvowel(char ch){
ch = tolower(ch);
return (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u');
}
inline bool isprime(int n){
if(n < 2 || (n%2 == 0 && n != 2)) return false;
for(int i = 3; i*i <= n; i++)
if(n%i == 0) return false;
return true;
}
class Union{
private:
vector <int> saizu, link;
public:
Union(int n){
saizu.assign(n+1, 1); link.resize(n+1);
iota(all(link), 0);
}
int find(int n){
if(link[n] == n) return n;
return link[n] = find(link[n]);
}
int same(int a, int b){
return find(a) == find(b);
}
void unite(int a, int b, int val){
if(same(a, b)) return;
a = find(a); b = find(b);
if(saizu[a] < saizu[b]) swap(a, b);
saizu[a] += saizu[b];
link[b] = a;
}
int getsize(int a){
return saizu[find(a)];
}
};
const int mod = 1e9+7;
ll mode(ll a){
a %= mod;
if(a < 0) a += mod;
return a;
}
ll subt(ll a, ll b){
return mode(mode(a)-mode(b));
}
ll add(ll a, ll b){
return mode(mode(a)+mode(b));
}
ll mult(ll a, ll b){
return mode(mode(a)*mode(b));
}
ll binpow(ll a, ll b){
ll res = 1;
while(b){
if(b&1) res = mult(res, a);
a = mult(a, a);
b >>= 1;
}
return res;
}
int main(){
int i;
ll n, k;
cin >> n >> k;
ll v[n];
ll sum = 0, mx = 0;
for(i = 0; i < n; i++){
cin >> v[i];
sum += v[i];
mx = max(mx, v[i]);
}
if(sum % k || mx > sum/k){
cout << -1;
return 0;
}
vector <ll> operations[1000007];
vector <pll> vec[k];
ll cnt = 0, ind = 0;
for(i = 0; i < n; i++){
cnt += v[i];
if(cnt >= sum/k){
vec[ind++].pb(mp(v[i]-cnt+sum/k, i));
cnt -= sum/k;
if(cnt) vec[ind].pb(mp(cnt, i));
}
else{
vec[ind].pb(mp(v[i], i));
}
}
ind = 0;
bool flag = 1;
while(flag){
flag = 0;
ll mn = 9e18;
for(auto it : vec) mn = min(mn, it.back().first);
operations[ind].pb(mn-1);
for(i = 0; i < k; i++){
operations[ind].pb(vec[i].back().second);
vec[i].back().first -= mn;
if(vec[i].back().first == 0) vec[i].pop_back();
}
ind++;
flag |= !vec[0].empty();
}
cout << ind << endl;
for(int i = 0; i < ind; i++){
auto it = operations[i];
for(auto to : it) cout << to+1 << ' ';
cout << endl;
}
return 0;
}
