#include <bits/stdc++.h>
using namespace std;
using LL = long long;
void solve() {
int n, d, m; cin >> n >> d >> m;
vector<pair<int, int > > v;
for (int i = 0; i < m; ++i) {
int x; cin >> x;
v.push_back({x, i + 1});
}
sort(v.begin(), v.end());
// for (auto [u, x] : v) cerr << u << " " << x << endl;
// cerr << "----------------------------------------------\n";
int lo = 1, hi = m;
vector<int> ans[n + 1], final[n + 1];
auto test = [&] (int numOfMachine) {
for (int i = 1; i <= n; ++i) ans[i].clear();
int cur = 0, tot = 0, day = 0;
for (int i = 0; i < m; ) {
int j = i;
if (day < v[i].first) cur = 0;
day = max(day, v[i].first);
while (j < m and v[i].first == v[j].first) {
if (day - v[j].first > d) return false;
ans[day].push_back(v[j].second);
cur++;
tot++;
j++;
// if (numOfMachine == 2) cerr << "#" << day << " " << tot << " " << cur << endl;
if (cur == numOfMachine) cur = 0, day++;
}
i = j;
}
return tot == m;
};
while (lo < hi) {
int mid = lo + (hi - lo) / 2;
if (test(mid)) {
hi = mid;
for (int i = 1; i <= n; ++i) {
final[i].clear();
for (auto u : ans[i]) final[i].push_back(u);
}
}
else lo = mid + 1;
}
cout << hi << "\n";
for (int i = 1; i <= n; ++i) {
for (auto u : final[i]) cout << u << " ";
cout << 0 << "\n";
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
}
