#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define MOD 1000000007
#define MODA 998244353
#define pb push_back
#define sortv(v) sort(v.begin(), v.end())
#define sorta(A, N) sort(A, A + N)
#define debug(x) cerr << #x << " is " << x;
#define rep(i, a, N) for (ll i = a; i < N; i++)
#define f first
#define s second
#define uniq(v) \
{ \
sort(v.begin(), v.end()); \
v.erase(unique(v.begin(), v.end()), v.end()); \
}
#define speed \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL);
using namespace std;
void solve(ll tcase)
{
ll N, D, M;
cin >> N >> D >> M;
vector<pair<ll, ll> > a(M);
rep(i, 0, M)
{
cin >> a[i].f;
a[i].f += D;
a[i].s = i;
}
sortv(a);
ll lo = 1, hi = M + 1;
while (lo < hi)
{
ll mid = (lo + hi) / 2;
ll pos = 0, flag = 1;
rep(day, 1, N + 1)
{
pos += mid;
ll x = min(pos, M);
ll last = a[x - 1].f;
if (last < day)
{
flag = 0;
break;
}
if (pos >= M)
break;
}
if (!flag)
lo = mid + 1;
else
hi = mid;
}
cout << hi << "\n";
ll pos = 0;
rep(day, 1, N + 1)
{
while (pos < M)
{
ll x = min(pos + hi, M);
rep(i, pos, x)
cout
<< a[i].s + 1 << ' ';
pos = x;
break;
}
cout << "0\n";
}
}
int main()
{
speed;
ll t = 1;
rep(i, 1, t + 1)
solve(i);
}
