#include <bits/stdc++.h>
#define ll long long
#define FAST \
ios::sync_with_stdio(false); \
cin.tie(NULL);
#define ld long double
// #define pb(x) push_back(x)
#define set(arr, x) memset(arr, x, sizeof(arr))
#define F0R(i, a) for (int i = 0; i < a; i++)
#define F1R(i, a) for (int i = 1; i <= a; i++)
#define all(x) (x).begin(), (x).end() // sort(all(vec))
// vec.resize(unique(all(vec)) - vec.begin());
// iota(p.begin(), p.end(), 0);
using namespace std;
int n, d, m;
pair<bool, vector<vector<int>>> valid(vector<pair<int, int>> &jobs, int mnMachine)
{
vector<vector<int>> schedule(n);
int need = 0;
for (int i = 1; i <= n; i++)
{
for (int j = 0; j < m; j++)
{
if(jobs[need].first > i) break;
if(jobs[need].first + d >= i)
{
schedule[i - 1].push_back(jobs[need++].second);
}
else
{
make_pair(false, schedule);
}
if (need == m) return make_pair(true, schedule);
}
}
return make_pair(false, schedule);
}
void solve()
{
cin >> n >> d >> m;
vector<pair<int, int>> jobs(m);
for (int i = 0; i < m; i++)
{
cin >> jobs[i].first;
jobs[i].second = i + 1;
}
sort(all(jobs));
vector<vector<int>> result;
int l = 1, r = m;
while (l < r)
{
int mid = (l + r) / 2;
pair<bool, vector<vector<int>>> res = valid(jobs, mid);
if (res.first)
{
r = mid;
result = res.second;
}
else
{
l = mid + 1;
}
}
cout << l << endl;
for (int i = 0; i < n; i++) {
for (int &idx : result[i]) cout << idx << " ";
cout << 0 << "\n";
}
}
int main()
{
FAST;
int t = 1;
// cin >> t;
while (t--)
{
solve();
};
// solve();
// cout << (2^4^5);
return 0;
}
