#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define ll long long
#define ld long double
#define all(_v) _v.begin(), _v.end()
#define sz(_v) (int)_v.size()
#define pii pair <int, int>
#define pll pair <ll, ll>
#define veci vector <int>
#define vecll vector <ll>
const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
const double PI = 3.1415926535897932384626433832795;
const double eps = 1e-9;
const int MOD1 = 1e9 + 7;
const int MOD2 = 998244353;
const int MAXN = 1e6 + 10;
int n, k;
ll a[MAXN];
vector <veci> ans;
vecll vals;
vector <vector <pll>> g;
void solve() {
cin >> n >> k;
ll sum = 0;
ll mx = 0;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
sum += a[i];
mx = max(mx, a[i]);
}
if(sum % k != 0 || mx > sum / k) {
cout << -1;
return;
}
ll p = 0;
vector <pll> cur;
for(int i = 1; i <= n; ++i) {
p += a[i];
if(p >= sum / k) {
cur.pb(mp(a[i] - p + sum / k, i));
g.pb(cur);
cur.clear();
p -= sum / k;
if(p != 0) cur.pb(mp(p, i));
} else cur.pb(mp(a[i], i));
}
if(!cur.empty()) g.pb(cur);
while(1) {
ll mn = 1e18;
for(int i = 0; i < sz(g); ++i) mn = min(mn, g[i].back().f);
vals.pb(mn);
bool ok = 0;
veci cr;
for(int i = 0; i < sz(g); ++i) {
cr.pb(g[i].back().s);
if(g[i].back().f == mn) g[i].pop_back();
else g[i].back().f -= mn;
if(g[i].empty()) ok = 1;
}
ans.pb(cr);
if(ok) break;
}
cout << sz(ans) << '\n';
for(int i = 0; i < sz(ans); ++i) {
cout << vals[i] << ' ';
for(auto j : ans[i]) cout << j << ' ';
cout << '\n';
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int CNT_TESTS = 1;
///cin >> CNT_TESTS;
for(int NUMCASE = 1; NUMCASE <= CNT_TESTS; ++NUMCASE) {
solve();
if(NUMCASE != CNT_TESTS) cout << '\n';
}
return 0;
}
