#include <bits/stdc++.h>
using ll = long long;
using ld = long double;
using namespace std;
const int MAXN = 2000001;
vector<vector<ll>> ans;
vector<pair<int, ll>> g[MAXN];
ll a[MAXN];
int main() {
#ifdef PAUNSVOKNO
freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false); cout.setf(ios::fixed); cout.precision(20); cout.tie(nullptr); cin.tie(nullptr);
int n, k;
cin >> n >> k;
ll s = 0;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
s += a[i];
}
if (s % k) {
return cout << -1 << "\n", 0;
}
int cur = 0;
s /= k;
ll left = s;
for (int i = 1; i <= n; ++i) {
if (a[i] > s) {
return cout << -1 << "\n", 0;
}
if (a[i] >= left) {
g[cur++].emplace_back(i, left);
if (a[i] != left) {
g[cur].emplace_back(i, a[i] - left);
}
left += (s - a[i]);
} else {
g[cur].emplace_back(i, a[i]);
left -= a[i];
}
}
while (!g[0].empty()) {
ll x = (1ll << 60);
ans.emplace_back(k + 1);
for (int i = 0; i < k; ++i) {
ans.back()[i + 1] = g[i].back().first;
x = min(x, g[i].back().second);
}
ans.back()[0] = x;
for (int i = 0; i < k; ++i) {
if (x == g[i].back().second) {
g[i].pop_back();
} else {
g[i].back().second -= x;
}
}
}
cout << ans.size() << "\n";
for (auto& v : ans) {
for (auto& t : v) {
cout << t << " ";
}
cout << "\n";
}
}
