#include <bits/stdc++.h>
using namespace std;
void solve()
{
struct job
{
int day;
int index;
};
int n, d;
int m;
cin >> n >> d >> m;
vector<job> jobs(m);
for (int j = 0; j < m; j++)
cin >> jobs[j].day, jobs[j].index = j;
sort(jobs.begin(), jobs.end(), [](const auto &lhs, const auto &rhs) -> bool
{ return lhs.day < rhs.day; });
auto valid = [&](const int &w) -> pair<bool, vector<vector<int>>>
{
vector<vector<int>> sc(n);
for (int i = 0, j = 0; i < n && j < m; i++)
{
for (int c = w; j < m && c > 0 && jobs[j].day <= i + 1; j++, c--)
{
if (i + 1 - jobs[j].day > d)
return {0, {}};
sc[i].push_back(jobs[j].index + 1);
}
}
return {1, sc};
};
int ans = m;
vector<vector<int>> schedule;
for (int l = 1; l < ans;)
{
int mid = (l + ans) / 2;
if (const auto &[s, v] = valid(mid); s)
{
ans = mid;
schedule = v;
}
else
l = mid + 1;
}
cout << ans << '\n';
for (const auto &ids : schedule)
{
for (const auto &id : ids)
cout << id << ' ';
cout << 0 << '\n';
}
}
int main()
{
ios_base::sync_with_stdio(false), cin.tie(NULL);
solve();
return 0;
}
