#include <bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define pii pair<int, int>
#define ll long long
int main()
{
int n, d, m;
cin >> n >> d >> m;
vector<vi> adj(n + 1);
for (int i = 1; i < m + 1; ++i)
{
int day;
cin >> day;
adj[day].push_back(i);
}
auto good = [&](int machines)
{
int curr_day = 0;
int job_requests = 0;
for (int i = 1; i < n + 1; ++i)
{
job_requests += adj[i].size();
curr_day += job_requests / machines;
job_requests %= machines;
if (curr_day > i + d) return false;
}
return true;
};
int lo = 1, hi = m;
while (lo < hi)
{
int mid = (lo + hi) / 2;
if (good(mid))
{
hi = mid;
}
else
{
lo = mid + 1;
}
}
cout << lo << endl;
queue<int> q;
for (int i = 1; i < n + 1; ++i)
{
for (int job: adj[i]) q.push(job);
int counter = 0;
while (counter < lo && !q.empty())
{
cout << q.front() << " ";
q.pop();
counter++;
}
cout << "0\n";
}
return 0;
}
