#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<pair<int, int>> vpi;
typedef vector<pair<ll, ll>> vpl;
#define pb(a) push_back(a)
#define pbr(a,b) pb(make_pair(a,b))
#define fr(i, a, b) for(int i = a; i <= b; i++)
#define rf(i, a, b) for(int i = a; i >= b; i--)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define F first
#define S second
ll M = 1e9 + 7; //998244353;
const int N = 100001;
ll binpow(ll a, ll b){ ll ans = 1; while(b > 0){ if(b&1) ans = (ans * a) % M; a = (a*a) % M; b >>= 1; } return ans; }
bool sS(pi p1, pi p2){ return (p1.S < p2.S); }
bool sF(pi p1, pi p2){ return (p1.F < p2.F); }
bool chk(int mid, int n, int m, int d, queue<int> q, int a[]){
fr(i, 1, n){
fr(j, 0, mid-1){
if(q.empty())
break;
int u = q.front();
if(a[u] > i)
break;
q.pop();
if(a[u]+d < i)
return 0;
}
}
if(q.empty())
return 1;
return 0;
}
void solve()
{
int n, d, m;
cin >> n >> d >> m;
vector<vi> vec(n-d+1);
int a[m+1];
fr(i, 1, m){
cin >> a[i];
vec[a[i]].pb(i);
}
queue<int> q;
fr(i, 1, n-d){
for(auto u: vec[i])
q.push(u);
}
int l = 0, r = m;
while(r > l+1){
// cout << l << " " << r << "\n";
int mid = (l+r) / 2;
if(chk(mid, n, m, d, q, a))
r = mid;
else
l = mid;
// cout << "\n";
}
cout << r << "\n";
fr(i, 1, n){
fr(j, 0, r-1){
if(q.empty())
break;
int u = q.front();
if(a[u] > i)
continue;
q.pop();
cout << u << " ";
}
cout << "0\n";
}
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// freopen(".in", "r", stdin);
// freopen(".out", "w", stdout);
int t=1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
// cout << "t: " << t << "\n";
solve();
}
return 0;
}
