#include<bits/stdc++.h>
using namespace std;
#define dbg(x) cerr << #x << " = " << x << endl;
#define fall(r,a,b) for(int r = a;r <= b;r++)
#define rfall(r,a,b) for(int r = a;r >= b;r--)
#define all(x) x.begin(), x.end()
#define int long long
#define pb push_back
#define endl "\n"
#define ff first
#define ss second
#define get(x,t) get<x>(t)
typedef pair<int,int> pii;
typedef tuple<int,int,int> tii;
typedef tuple<int,int,int,int> tii1;
const int maxn = 2e5+10;
const int mod = 1e9+7;
const int inf = 1e17;
vector<pii> v;
bool ok(int n,int d,int m){
vector<pii> aux = v;
fall(r,1,n){
int mn = min(m,(int)aux.size());
fall(i,1,mn){
int ba = (int)aux.back().ff;
if(ba<=r and r<=ba+d) aux.pop_back();
else if(ba<=r and r>ba+d) return 0;
}
}
if(aux.empty()) return 1;
else return 0;
}
void bb(int n,int d){
int i = 1;
int f = v.size();
while(i<=f){
int m = (i+f)/2;
if(ok(n,d,m)) f = m-1;
else i = m+1;
}
cout << i << endl;
fall(r,1,n){
int mn = min(i,(int)v.size());
fall(j,1,mn){
int ba = (int)v.back().ss;
cout << ba << " ";
v.pop_back();
}
cout << 0 << endl;
}
}
int32_t main() {
//freopen("socdist.in", "r", stdin);
//freopen("socdist.out", "w", stdout);
ios::sync_with_stdio(0);
cin.tie(NULL);
int N,n,m,q,k;
int a,b,c,d;
int x,y;
cin >> n >> d >> m;
fall(r,1,m){
cin >> a;
v.pb({a,r});
}
sort(all(v));
reverse(all(v));
bb(n,d);
}
