#include <bits/stdc++.h>
using namespace std;
#define int int64_t
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
typedef vector<vii> vvii;
typedef vector<bool> vb;
typedef vector<vb> vvb;
#define x first
#define y second
#define pb push_back
#define loop(i,s,e) for(int i=s;i<e;i++)
#define loopr(i,s,e) for(int i=e-1; i>=s;i--)
#define chkmax(a,b) a=max(a,b)
#define chkmin(a,b) a=min(a,b)
#define all(a) a.begin(),a.end()
#define fast {ios_base::sync_with_stdio(0); cin.tie(0);}
const int inf = 1e18;
const int INF = 1e9;
int n, d, m;
int32_t main()
{
fast;
cin >> n >> d >> m;
vector<set<int>> starts_in(n+1);
vector<set<int>> ends_in(n+1);
vi rel_days;
vi tasks(m);
loop(i,0,m){
cin >> tasks[i];
int s=tasks[i], e=s+d;
starts_in[s].insert(i);
ends_in[e].insert(i);
}
loop(i,1,n+1) if(!starts_in[i].empty()) rel_days.pb(i);
int cnt_tasks=0;
int cnt_machine=0;
vvi tasks_per_day(n+1);
while(cnt_tasks<m){
cnt_machine++;
set<ii> cur_tasks;
auto p_day = 0;
int cur_day=0;
while(cur_day<=n && (p_day < rel_days.size() || !cur_tasks.empty())){
if(cur_tasks.empty()){
cur_day = rel_days[p_day]; p_day++;
}
else if(cur_day == rel_days[p_day]) p_day++;
//inserting today's tasks
if(!starts_in[cur_day].empty()){
cur_tasks.insert({cur_day+d, starts_in[cur_day].size()});
}
//finding current task
ii cur = *cur_tasks.begin();
int cur_day_t = cur.x, cur_cnt_t = cur.y;
cur_tasks.erase(cur_tasks.begin());
if(cur_cnt_t > 1) cur_tasks.insert({cur_day_t, cur_cnt_t-1});
int cur_t = *(ends_in[cur_day_t].begin());
tasks_per_day[cur_day].pb(cur_t);
starts_in[tasks[cur_t]].erase(starts_in[tasks[cur_t]].find(cur_t));
ends_in[cur_day_t].erase(ends_in[cur_day_t].begin());
//erasing tasks that end today
auto ers = cur_tasks.lower_bound({cur_day,1});
if(ers != cur_tasks.end() && (*ers).x == cur_day){
cur_tasks.erase(ers);
}
cnt_tasks++;
cur_day++;
}
rel_days.clear();
loop(i,1,n+1) if(!starts_in[i].empty()) rel_days.pb(i);
}
cout << cnt_machine << endl;
loop(i,1,n+1){
for(int t: tasks_per_day[i]) cout << t+1 << " ";
cout << "0\n";
}
return 0;
}
