/*
ID: hedichehaidar
TASK: cowtour
LANG: C++11
*/
#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd pair<double,double>
#define vdd vector<pdd>
#define dte tuple<double , double , double>
using namespace std;
const int INF = 1000*1000*1000; // 1 e 9
const int MOD = 998244353;
const double EPS = 0.000000001; // 1 e -9
const ll inf = (ll)1e18;
vi task[(int)1e6 + 10];
int need[(int)1e5 + 10];
int main(){
//ifstream fin ("testing.txt");
//ofstream fout ("output.txt");
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
ll n , d , m; cin>>n>>d>>m;
for(int i = 0 ; i < m ; i++){
int x; cin>>x; task[x].pb(i + 1);
}
int l = 1 , r = m , ans = m;
while(l <= r){
int mid = (l+r) / 2;
bool ok = true;
int cur = 0 , all = 0;
for(int i = 1 ; i <= n ; i++) need[i] = 0;
for(int i = 1 ; i <= n ; i++){
need[i] += need[i - 1];
//if(mid == 1) cout << need[i] << " " << cur << " ";
need[i + d] += task[i].size();
all += task[i].size();
cur += min(all , mid);
all -= min(all , mid);
if(cur < need[i]){
ok = false; break;
}
}
//if(mid == 1) cout << "\n";
if(ok){
ans = mid; r = mid - 1;
}
else l = mid + 1;
}
queue<int> q;
cout << ans << "\n";
for(int i = 1 ; i <= n ; i++){
for(auto c : task[i]) q.push(c);
for(int j = 0 ; j < ans ; j++){
if(q.empty()) break;
cout << q.front() << " ";
q.pop();
}
cout << 0 << "\n";
}
return 0;
}
/*
Think of : BS / DFS / BFS / SSSP / SCC / MSP / MAX FLOW / TOPSORT / LCA / MATRIX / DP(bitmask) / 2 POINTERS / SEG TREE / MATH / UN FIND / MO / HLD
Read the statement CAREFULLY !!
Make a GREADY APPROACH !!!! (start from highest / lowest)
Make your own TESTS !!
Be careful from CORNER CASES !
*/
