#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ss second
#define ff first
#define pb push_back
#define mk make_pair
#define mt make_tuple
#define all(x) (x).begin(), (x).end()
ll n,m,a[200100],k;
bool go(ll mid){
int o=0,d=0;
for(int i=0;i<m;i++){
if(d-a[i]>=k)
return false;
o++;
if(o>=mid){
o=0;
d++;
}
}
return true;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>k>>m;
vector<pair<ll,int> >v;
for(int i=0;i<m;i++){
cin>>a[i];
v.pb({a[i],i});
}
ll l=0,r=1e9,ans=1e9;
while(l<=r){
ll mid=(l+r)/2;
if(go(mid)){
r=mid-1;
ans=mid;
}
else{
l=mid+1;
}
}
cout<<ans<<endl;
sort(v.begin(),v.end());
int k=0;
for(int i=0;i<n;i++){
int o=0;
for(int j=k;j<m;j++){
cout<<v[j].ss+1<<" ";
o++;
k++;
if(o==ans)
break;
}
cout<<0<<endl;
}
}
