#include <bits/stdc++.h>
using namespace std;
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
#define ll long long
#define ld long double
#define all(a) (a).begin(), (a).end()
#define lid chs[id].first
#define rid chs[id].second
#define mid ((r + l) >> 1)
#define sui cout.tie(NULL); cin.tie(NULL); ios_base::sync_with_stdio(false)
const int MAX_N = 5e5 + 5;
const int MOD = 1e9 + 7;
const ll INF = 1e18;
const ld EPS = 1e-9;
const int LOG = 60;
void solve() {
int n, k;
cin >> n >> k;
ll a[n];
ll ma = 0;
ll sum = 0;
for (int i = 0; i < n; i++) cin >> a[i], ma = max(ma, a[i]), sum += a[i];
if (sum % k || ma > sum / k)
{
cout << -1 << "\n";
return;
}
vector<pair<int, ll>> al[k];
int ind = 0;
ll last = 0;
for (int i = 0; i < n; i++)
{
if (sum / k - last >= a[i]) al[ind].push_back({i, a[i]}), last += a[i];
else
{
al[ind].push_back({i, sum / k - last});
a[i] -= sum / k - last;
last = a[i];
ind++;
al[ind].push_back({i, a[i]});
}
}
for (int i = 0; i < k; i++) reverse(all(al[i]));
vector<vector<ll>> ans;
last = 0;
while (last < sum / k)
{
ll cnt = INF;
for (int i = 0; i < k; i++)
{
while (al[i].back().second == 0) al[i].pop_back();
cnt = min(cnt, al[i].back().second);
}
vector<ll> ne({cnt});
for (int i = 0; i < k; i++)
{
ne.push_back(al[i].back().first + 1);
al[i].back().second -= cnt;
}
last += cnt;
ans.push_back(ne);
}
cout << ans.size() << "\n";
for (auto x : ans)
{
for (ll y : x) cout << y << " ";
cout << "\n";
}
}
int main() {
sui;
int tc = 1;
//cin >> tc;
for (int t = 1; t <= tc; t++) {
solve();
}
}
