#include <bits/stdc++.h>
#define int long long
using namespace std;
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
//freopen("schedule.in","r",stdin);
int n,d,m; cin>>n>>d>>m;
vector<pair<int,int>> jobs(m);
for (int i=0;i<m;i++) {
cin>>jobs[i].first;
jobs[i].second = i+1;
}
sort(jobs.begin(),jobs.end());
int lo=1,hi=m;
auto test=[&](int x) {
int pt=0,day=0;
while (pt<m) {
day++;
if ((jobs[pt].first-d)>day) return false;
int had=0;
while (pt<m && had<x) {
if (jobs[pt].first>day) break;
pt++;
had++;
}
}
return (day<=n);
} ;
while (lo<hi) {
int mid=lo+(hi-lo)/2;
if (test(mid)) hi = mid;
else lo = mid+1;
}
cout<<lo<<"\n";
int pt=0,day=0;
while (pt<m) {
day++;
int had=0;
while (pt<m && had<lo) {
if (jobs[pt].first>day) break;
cout<<jobs[pt].second<<" ";
pt++;
had++;
}
cout<<0<<"\n";
}
for (int i=day;i<n;i++) cout<<0<<"\n";
return 0;
}
// if you get WA, go and read the question carefully again
// Then read the code for mixed variables, mistype, not considering a condition, etc.
