///TRAN THAI BAO :3
#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
typedef pair<int, int> pii;
#define maxN 1000007
int n, m, d;
pii a[maxN];
bool check(int k)
{
int i = 1;
int day = 1;
while(day <= n && i <= m)
{
for(int j = 1; j <= k; j++)
{
if(i > m)
return true;
if(a[i].first <= day)
{
if(day - a[i].first > d)
return false;
i++;
}
else break;
}
day++;
}
if(i > m)
return true;
return false;
}
void getAns(int k)
{
int i = 1;
int day = 1;
while(day <= n)
{
for(int j = 1; j <= k; j++)
{
if(i > m)
break;
if(a[i].first <= day)
{
cout << a[i].second << ' ';
i++;
}
else break;
}
cout << "0\n";
day++;
}
}
void solve()
{
cin >> n >> d >> m;
for(int i = 1; i <= m; i++)
{
cin >> a[i].first;
a[i].second = i;
}
sort(a+1, a+m+1);
int lo = 1, hi = m, mid, minAns = m;
while(lo <= hi)
{
mid = (lo+hi)/2;
if(check(mid))
{
hi = mid-1;
minAns = min(minAns, mid);
}
else lo = mid+1;
}
cout << minAns << '\n';
getAns(minAns);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
return 0;
}
