#include <bits/stdc++.h>
using namespace std;
pair<int, int> t[1'100'002];
int zli[1'100'001];
vector <int> zli2[100'100];
int n, m, d;
bool war(int x)
{
int st_free = 1;
for (int i = 1; i <= n; i++)
{
zli[i] = 0;
}
for (int i = 1; i <= m; i++)
{
while (st_free < t[i].first || zli[st_free] == x)
{
st_free++;
}
zli[st_free]++;
if (st_free - t[i].first > d)
{
return false;
}
}
return true;
}
void ans(int x)
{
int st_free = 1;
for (int i = 1; i <= n; i++)
{
zli[i] = 0;
}
for (int i = 1; i <= m; i++)
{
if (zli[st_free] == x)
{
st_free++;
}
while (st_free < t[i].first)
{
st_free++;
}
zli[st_free]++;
zli2[st_free].push_back(t[i].second);
}
for (int i = 1; i <= n; i++)
{
for (auto j : zli2[i])
{
cout << j << ' ';
}
cout << "0\n";
}
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> d >> m;
for (int i = 1; i <= m; i++)
{
cin >> t[i].first;
t[i].second = i;
}
sort (t+1, t + m+1);
int beg = 1;
int en = m;
while (beg < en)
{
int x = (beg + en)/2;
if (war(x))
{
en = x;
}
else
{
beg = x + 1;
}
}
cout << en << '\n';
ans(en);
}
//10 1 20
// 7 9 1 9 4 1 5 9 7 7 2 3 2 4 3 2 3 3 7 2
