#include <bits/stdc++.h>
using namespace std;
#define fastio() \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL)
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vll vector<ll>
#define vpii vector<pii>
#define vpll vector<pll>
#define vvi vector<vi>
#define ff first
#define ss second
#define endl "\n"
#define pb(x) push_back(x)
#define pp() pop_back()
#define inf MAX_INT
#define dvg(x) cout << #x << " " << x << endl;
#define dvg2(x, y) cout << #x << " " << x << " " << #y << " " << y << endl;
#define dvgv(x) \
cout << #x << " { "; \
for (auto i : x) \
{ \
cout << i << " "; \
} \
cout << "}" << endl;
#define dvgp(x) cout << #x " {" << x.ff << ", " << x.ss << "}" << endl;
int dx[]{-1, 0, 1, 0, 1, 1, -1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
int const N = 1e5 + 10;
vpii v;
vvi ans;
int n, d, m;
bool ok(int x)
{
int day = 1, machines = 1;
ans = vvi(n + 1, vi());
for (int i = 0; i < m; i++)
{
while (day < v[i].ff)
{
day++;
machines = 1;
}
if (day - v[i].ff > d)
{
return 0;
}
ans[day].pb(v[i].ss);
machines++;
if (machines > x)
{
day++;
machines = 1;
}
}
return 1;
}
int main()
{
fastio();
cin >> n >> d >> m;
v = vpii(m);
for (int i = 0; i < m; i++)
{
cin >> v[i].ff;
v[i].ss = i + 1;
}
sort(v.begin(), v.end());
int lo = 0, hi = 1e5 + 12;
while (lo + 1 < hi)
{
int mid = (hi + lo) / 2;
if (ok(mid))
hi = mid;
else
lo = mid;
}
cout << hi << endl;
ok(hi);
for (int i = 1; i <= n; i++)
{
for (auto j : ans[i])
cout << j << " ";
cout << 0 << endl;
}
}
