#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
using pi = pair<int,int>;
using vi = vector<int>;
int n, m, d;
pair<bool, vector<vi>> isFeasible(vector<pair<int,int>>& jobs, int machineCount) {
vector<vi> schedule(n);
int reqNum=0;
for (int day=1; day<=n; ++day) {
for (int j=0; j<machineCount; ++j) {
if (jobs[reqNum].first>day) break;
if (jobs[reqNum].first+d>=day) {
schedule[day-1].push_back(jobs[reqNum++].second);
} else {
return make_pair(false, schedule);
}
if (reqNum==m) {
return make_pair(true, schedule);
}
}
}
return make_pair(false, schedule);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>d>>m;
vector<pi> jobs(m);
for (int i=0; i<m; ++i) {
int day;
cin>>day;
jobs[i]={day, i+1};
}
sort(begin(jobs), end(jobs));
vector<vi> result;
int l=1, r=m;
while (l<r) {
int machineNum=l+(r-l)/2;
pair<bool, vector<vi>> curResult = isFeasible(jobs, machineNum);
if (curResult.first) {
r=machineNum;
result=curResult.second;
} else {
l=machineNum+1;
}
}
cout<<l<<"\n";
for (int i=0; i<n; ++i) {
for (int& idx : result[i]) {
cout<<idx<<" ";
}
cout<<0<<"\n";
}
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
