#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <cmath>
#define ll long long
#define all(x) x.begin(), x.end()
#define pi pair<int,int>
#define f first
#define s second
#define CHECKPOINT cout << "got here" << endl;
#define pb push_back
#define create_pfixsum(a,n,p) for(int i = 1; i < n; i++){p[i] = p[i-1] + a[i];}
using namespace std;
int n, d, m;
vector<vector<int>> ans;
vector<pi> a;
bool f(int l){
int i = 0;
int cur;
for(int day = 1; day <= n; day++){
cur = 0;
while(i < m && a[i].f <= day && day <= a[i].f+d && cur < l){
cur++;
i++;
}
}
if(i >= m){
return true;
}
return false;
}
void printans(int l){
ans.clear();
ans.resize(n);
int i = 0;
int cur;
for(int day = 1; day <= n; day++){
cur = 0;
while(i < m && a[i].f <= day && day <= a[i].f+d && cur < l){
cout << a[i].s << ' ';
cur++;
i++;
}
cout << 0 << endl;
}
}
int main() {
cin >> n >> d >> m;
a.resize(m);
for(int i = 0; i < m ; i++){
cin >> a[i].f;
a[i].s = i+1;
}
sort(all(a));
int l = 1, r = m;
while(l < r){
int mid = l + (r-l) / 2;
if(f(mid)){
r = mid;
} else {
l = mid+1;
}
}
cout << l << endl;
printans(l);
}
