#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define MOD 1000000007
#define MODA 998244353
#define pb push_back
#define mp make_pair
#define sortv(v) sort(v.begin(), v.end())
#define sorta(A, N) sort(A, A + N)
#define debug(x) cerr << #x << " is " << x;
#define rep(i, a, N) for (ll i = a; i < N; i++)
#define f first
#define s second
#define uniq(v) \
{ \
sort(v.begin(), v.end()); \
v.erase(unique(v.begin(), v.end()), v.end()); \
}
#define speed \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL);
using namespace std;
ll N, D, M;
pair<bool, vector<vector<ll> > > isFeasible(const vector<pair<ll, ll> > &jobs, int machineCount)
{
vector<vector<ll> > schedule(N);
ll reqNum = 0;
rep(day, 1, N + 1)
{
rep(j, 0, machineCount)
{
if (jobs[reqNum].first > day)
break;
if (jobs[reqNum].first + D >= day)
schedule[day - 1].push_back(jobs[reqNum++].second);
else
return mp(false, schedule);
if (reqNum == M)
return mp(true, schedule);
}
}
return mp(false, schedule);
}
void solve(ll tcase)
{
cin >> N >> D >> M;
vector<pair<ll, ll> > jobs(M);
rep(i, 0, M)
{
ll day;
cin >> day;
jobs[i] = mp(day, i + 1);
}
sortv(jobs);
vector<vector<ll> > result;
ll l = 1, r = M;
while (l < r)
{
ll machineNum = (l + r) / 2;
pair<bool, vector<vector<ll> > > curResult = isFeasible(jobs, machineNum);
if (curResult.first)
{
r = machineNum;
result = curResult.second;
}
else
l = machineNum + 1;
}
cout << l << "\n";
rep(i, 0, N)
{
for (ll &idx : result[i])
cout << idx << " ";
cout << 0 << "\n";
}
}
int main()
{
speed;
ll t = 1;
rep(i, 1, t + 1)
solve(i);
}
