#include <bits/stdc++.h>
using namespace std;
using LL = long long;
int main() {
cin.tie(nullptr)->ios_base::sync_with_stdio(false);
int days, delay, req;
cin >> days >> delay >> req;
vector < pair <int, int> > v(req);
for (int i = 0; i < req; i++) {
int day;
cin >> day;
v[i] = {day, i + 1};
}
sort(v.begin(), v.end());
vector < vector <int> > ans;
int left = 1, right = req;
while (left < right) {
int mid = (left + right) >> 1;
int cur_req = 0;
vector < vector <int> > adj(days);
bool ok = false;
for (int i = 1; i <= days; i++) {
for (int j = 0; j < mid; j++) {
if (i < v[cur_req].first) break;
if (i <= v[cur_req].first + delay) adj[i - 1].push_back(v[cur_req++].second);
else break;
if (cur_req == req) ok = true;
}
}
if (ok) {
right = mid;
ans = adj;
} else {
left = mid + 1;
}
}
cout << right << '\n';
for (int i = 0; i < days; i++) {
for (auto c : ans[i]) cout << c << ' ';
cout << 0 << '\n';
}
return 0;
}
