#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].first+=d;
jobs[i].second = i+1;
}
sort(jobs.begin(),jobs.end());
int lo=1,hi=m;
auto test=[&](int x) {
int curr=0,day=1;
while (curr<m) {
curr = min(m,curr+x);
if (jobs[curr-1].first<day) return false;
day++;
}
return (day-1)<=n;
} ;
while (lo<hi) {
int mid=lo+(hi-lo)/2;
if (test(mid)) hi = mid;
else lo = mid+1;
}
cout<<lo<<"\n";
int curr=0,last=0,day=1;
while (curr<m) {
curr = min(m,curr+lo);
for (int i=last;i<curr;i++) cout<<jobs[i].second<<" ";
cout<<0<<"\n";
day++;
last = curr;
}
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.
