#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
//template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
//find_by_order, order_of_key
#define ll long long int
#define fastio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define mod 1000000007
#define inf 1e18
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define ff first
#define ss second
#define PI 3.141592653589793238462
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define iter(n) for (auto &el : n)
#define rep(i, init, n) for (ll i = init; i < (ll)n; i++)
#define rev(i, n, init) for (ll i = (ll)n; i >= init; i--)
#define V vector<int>
#define VV vector<V>
#define Vll vector<ll>
#define VVll vector<Vll>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define Vpii vector<pii>
#define Vpll vector<pll>
#define Mpll map<ll,ll>
void fileIO(string filename) {
freopen((filename + ".in").c_str(), "r", stdin);
freopen((filename + ".out").c_str(), "w", stdout);
}
void fileIN(string filename) {freopen((filename).c_str(), "r", stdin);}
void fileOUT(string filename) {freopen((filename).c_str(), "w", stdout);}
bool comparator(pair<ll, ll> a, pair<ll, ll> b){ // Ascending First
return a.ff < b.ff;
}
// 48-57 -> 0-9
// 65-90 -> A-Z
// 97-122 -> a-z
bool check(Mpll m, ll n, ll d, ll machines){
if(machines == 0) return false;
ll prev = 0;
rep(i,1,n-d+1){
if(prev/machines + m[i]/machines - 1 <= d){
prev = prev - machines + m[i];
}else return false;
}
return true;
}
void solve()
{
ll n,d,m;
cin>>n>>d>>m;
Mpll mp;
Vpll v(m);
ll x,y;
rep(i,0,m){
cin>>x;
v[i] = {x,i+1};
mp[x]++;
}
ll l = 0;
ll r = 2*m;
ll ans = 0;
while(l<=r){
ll mid = l + (r-l)/2;
if(check(mp,n,d,mid)){
ans = mid;
// cout<<mid<<endl;
r = mid - 1;
}else l = mid + 1;
}
cout<<ans<<endl;
sort(all(v));
ll div;
if(m%ans == 0){
div = m/ans;
}else{
div = m/ans + 1;
}
ll ind = 0;
rep(i,0,div){
ll j = 0;
while(j<ans && ind<sz(v)){
cout<<v[ind].ss<<" ";
j++;
ind++;
}
cout<<0<<endl;
}
rep(i,0,n-div){
cout<<0<<endl;
}
return;
}
int main()
{
fastio
//fileIO("");
//fileIN("");
//fileOUT("");
ll tc = 1;
//cin>>tc;
while(tc--){
solve();
}
return 0;
}
