#include <bits/stdc++.h>
using namespace std;
#define pb push_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
int n, d, m, a;
vvi dayIndexes;
bool check(int machines){
vi available(n + 1, machines);
for (int i = 1; i <= n - d; i++)
{
int jobs = dayIndexes[i].size();
for (int j = i; j <= i + d; j++)
{
if(available[j] >= jobs){
available[j] -= jobs;
jobs = 0;
} else {
jobs -= available[j];
available[j] = 0;
}
}
if(jobs) return false;
}
return true;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> d >> m;
dayIndexes = vvi(n + 1);
for (int i = 1; i <= m; i++)
{
cin >> a;
dayIndexes[a].pb(i);
}
ll lo = 1, hi = 1000000;
while(lo <= hi){
ll mid = (lo + hi)/2;
if(check(mid)) hi = mid - 1;
else lo = mid + 1;
}
cout << lo << '\n';
int curday = 1;
for (int i = 1; i <= n; i++)
{
int machines = lo;
while(machines--){
while(curday <= n && dayIndexes[curday].empty()) curday++;
if(curday > n) break;
cout << dayIndexes[curday].back() << " ";
dayIndexes[curday].pop_back();
}
cout << "0\n";
}
}
