#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "../Library/debug.h"
#else
#define dbg(x...)
#endif
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) for (int i = 0; i < (a); ++i)
#define FORd(i, a, b) for (int i = (b) - 1; i >= (a); --i)
#define F0Rd(i, a) for (int i = (a) - 1; i >= 0; --i)
#define trav(a, x) for (auto& a : x)
#define f first
#define s second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
const char nl = '\n';
const int INF = 1e9;
const int MOD = 1e9 + 7;
void solve(){
int n,d,m;
cin>>n>>d>>m;
vpi a(m);
F0R(i,m){
cin>>a[i].f;
a[i].f--;
a[i].s=i;
}
sort(all(a));
int l=1,r=1e6;
int ans=0;
while(l<=r){
int mid=(l+r)/2,j=0;
bool f=false;
F0R(i,n){
int e=min(j+mid,m);
if(j<m&&a[j].f+d<i){
f=true;
break;
}
while(j<e&&a[j].f+d>=i&&a[j].f<=i)
j++;
}
if(j<m) f=true;
if(f) l=mid+1;
else{
r=mid-1;
ans=mid;
}
}
cout<<ans<<nl;
int j=0;
F0R(i,n){
int e=min(j+ans,m);
while(j<e&&a[j].f+d>=i&&a[j].f<=i){
cout<<a[j].s+1<<" ";
j++;
}
cout<<"0\n";
}
}
int32_t main(){
ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int TC = 1;
// cin >> TC;
while(TC--){
solve();
}
return 0;
}
