#include <bits/stdc++.h>
using namespace std;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, d, m;
cin >> n >> d >> m;
vector<int> reqs(m), ord(m);
for (int &x : reqs) cin >> x, x--;
for (int i = 0; i < m; i++) ord[i] = i;
sort(ord.begin(), ord.end(), [&] (int i, int j) { return reqs[i] < reqs[j]; });
int lo = 0, hi = m;
vector<vector<int>> ans;
while (hi - lo > 1) {
int mid = (lo + hi) / 2;
queue<int> todo;
bool good = true;
int j = 0;
vector<vector<int>> tmp(n);
for (int i = 0; i < n; i++) {
while (j < m && reqs[ord[j]] == i) todo.push(ord[j++]);
for (int k = 0; k < mid && todo.size(); k++) {
if (i - todo.front() > d) good = false;
tmp[i].push_back(todo.front());
todo.pop();
}
}
if (todo.size() || good == false) lo = mid;
else {
ans = tmp;
hi = mid;
}
}
cout << hi << '\n';
for (int i = 0; i < n; i++) {
for (int x : ans[i]) cout << x + 1 << ' ';
cout << "0\n";
}
}
