#include <bits/stdc++.h>
#include <limits.h>
#define ll long long
#define ull unsigned long long
#define INF 1000000007
#define fastio() \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL)
using namespace std;
ll n, d, t;
vector<pair<ll, ll>> dates;
vector<vector<ll>> ans;
bool ok(ll x)
{
ans = vector<vector<ll>>(n + 1, vector<ll>());
ll machines = 1;
ll day = 1;
for (ll i = 1; i <= t; i++)
{
if (day < dates[i].first)
{
day = dates[i].first;
machines = 1;
}
if (day - dates[i].first > d)
return 0;
++machines;
ans[day].push_back(dates[i].second);
if (machines > x)
{
// ans.push_back(tmp);
// tmp.clear();
machines = 1;
++day;
}
}
return true;
}
int main()
{
fastio();
cin >> n >> d >> t;
dates.push_back({-1, -1});
for (ll i = 1; i <= t; i++)
{
ll x;
cin >> x;
dates.push_back({x, i});
}
sort(dates.begin(), dates.end());
ll l = 0;
ll r = 1e5 + 12;
while (r > l + 1)
{
ll m = l + (r - l) / 2;
if (ok(m))
r = m;
else
l = m;
}
ok(r);
cout << r << "\n";
for (int i = 1; i <= n; i++)
{
for (auto j : ans[i])
cout << j << " ";
cout << 0 << endl;
}
return 0;
}
