#include <bits/stdc++.h>
using namespace std;
struct Job {
int day, id;
Job(int d, int i) : day(d), id(i) {}
Job() : Job(0, 0) {}
bool operator<(const Job &j) const {
if(day!=j.day) return day<j.day;
return id>j.id;
}
};
#define MAXM 1001000
#define MAXN 100100
Job jobs[MAXM];
vector<int> ans[MAXN];
int n, d, m;
bool can(int qnt) {
for(int i=1;i<=n;i++) ans[i].clear();
int j=0;
for(int i=1;i<=n;i++) {
while(ans[i].size()<qnt&&j<m&&i>=jobs[j].day) {
if(jobs[j].day+d<i) return false;
ans[i].push_back(jobs[j].id);
j++;
}
}
return j==m;
}
int main() {
cin.tie(nullptr);
ios::sync_with_stdio(false);
cin >> n >> d >> m;
for(int i=0;i<m;i++) cin >> jobs[i].day;
for(int i=0;i<m;i++) jobs[i].id=i+1;
sort(jobs, jobs+m);
int l=1, r=m;
while(l<r) {
int mid=(l+r)/2;
if(can(mid)) r=mid;
else l=mid+1;
}
can(l);
cout << l << "\n";
for(int i=1;i<=n;i++) {
for(auto v : ans[i]) cout << v << " ";
cout << "0\n";
}
return 0;
}
