#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
using namespace std;
int N, D, M;
vector<pair<int, int>> jobs;
pair<bool, vector<vi>> check(const vector<pair<int, int>> &jobs, int machine)
{
vector<vi> schedule(N);
int id_job = 0;
for(int i=1; i<=N; i++)
{
for(int cur_machine=0; cur_machine<machine; cur_machine++)
{
if (jobs[id_job].fi > i) break;
if (jobs[id_job].fi + D >= i)
{
schedule[i - 1].pb(jobs[id_job++].se);
} else return make_pair(false, schedule);
if (id_job == 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++)
{
int x;
cin >> x;
jobs[i] = make_pair(x, i + 1);
}
sort(jobs.begin(), jobs.end());
vector<vi> ans;
int l = 1, r = M;
while(l < r)
{
int m = (l + r) >> 1;
pair<bool, vector<vi>> curResult = check(jobs, m);
if (curResult.fi)
{
r = m;
ans = curResult.se;
} else
{
l = m + 1;
}
}
cout << l << "\n";
for(int i=0; i<N; i++)
{
for(int &idx : ans[i])
{
cout << idx << " ";
}
cout << 0 << "\n";
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
return 0;
}
