#include <bits/stdc++.h>
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define fast ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define all(v) v.begin(),v.end()
#define pb push_back
#define sz size()
#define ft first
#define sd second
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef unsigned long long ull;
const int N = 1e6 + 5;
const ll M = 1e8;
const ll inf = 1e18;
const ll mod = 1e9;
const double Pi = acos(-1);
ll binpow(ll x, ll ti) { ll res = 1;while (ti){if(ti & 1)res *= x;x *= x;ti >>= 1; x %= mod; res %= mod;} return res;}
ll binmul(ll x, ll ti) { ll res = 0;while (ti){if(ti & 1)res += x;x += x;ti >>= 1; x %= mod; res %= mod;} return res;}
ll nok(ll a, ll b) { return (a*b)/__gcd(abs(a),abs(b)) * (a*b > 0 ? 1 : -1); }
bool odd(ll n) { return (n % 2 == 1); }
bool even(ll n) { return (n % 2 == 0); }
ll n, k, sum, l[N], mx, cnt;
pll a[N], b[N];
vector <pll> q[N];
const void solve(/*Armashka*/) {
cin >> n >> k;
for (int i = 1; i <= n; ++ i) cin >> a[i].ft, a[i].sd = i;
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; ++ i) b[i] = a[i], sum += a[i].ft, mx = max(mx, a[i].ft);
if (sum % k || mx > sum / k) {
cout << "-1\n";
return;
}
ll s = 0, cur = 1;
for (int i = 1; i <= n; ++ i) {
if (s + a[i].ft <= sum / k) {
q[cur].pb({a[i].ft, a[i].sd});
s += a[i].ft;
if (s == sum / k) {
s = 0;
++ cur;
}
} else {
q[cur].pb({(sum / k) - s, a[i].sd});
++ cur;
s = a[i].ft - ((sum / k) - s);
q[cur].pb({s, a[i].sd});
}
}
while (1) {
multiset <pll> st;
for (int i = 1; i <= k; ++ i) {
if (l[i] < q[i].sz) st.insert({q[i][l[i]].ft, i});
}
if (st.empty()) break;
for (auto [x, pos] : st) {
if (x == st.begin()->ft) q[pos][l[pos]].ft = 0, ++ l[pos];
else q[pos][l[pos]].ft -= st.begin()->ft;
}
++ cnt;
}
cout << cnt << "\n";
for (int i = 1; i <= k; ++ i) q[i].clear();
s = 0, cur = 1;
for (int i = 1; i <= n; ++ i) {
if (s + a[i].ft <= sum / k) {
q[cur].pb({a[i].ft, a[i].sd});
s += a[i].ft;
if (s == sum / k) {
s = 0;
++ cur;
}
} else {
q[cur].pb({(sum / k) - s, a[i].sd});
++ cur;
s = a[i].ft - ((sum / k) - s);
q[cur].pb({s, a[i].sd});
}
}
for (int i = 1; i <= k; ++ i) l[i] = 0;
while (1) {
multiset <pair<pll, ll>> st;
for (int i = 1; i <= k; ++ i) {
if (l[i] < q[i].sz) st.insert({q[i][l[i]], i});
}
if (st.empty()) break;
cout << st.begin()->ft.ft << " ";
for (auto [x, pos] : st) {
if (x.ft == st.begin()->ft.ft) q[pos][l[pos]].ft = 0, ++ l[pos];
else q[pos][l[pos]].ft -= st.begin()->ft.ft;
cout << x.sd << " ";
}
cout << "\n";
}
}
signed main() {
fast;
//freopen("divide.in", "r", stdin);
//freopen("divide.out", "w", stdout);
int tt = 1;
//cin >> tt;
while (tt --) {
solve();
}
}
/*
5 4 4
1 2
3 1
3 4
5 3
4 5 2 3
2 1 3 1
1 3 5
2 3 4 5
2 1 3 1
*/
