#include <bits/stdc++.h>
using namespace std;
#define print(l) for(auto i:l) cout<<i<<" ";cout<<endl;
#define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i];
#define int long long
#define pb push_back
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define all(l) l.begin(),l.end()
#define pii pair<int,int>
#define fi first
#define se second
const int M = 1e9+7;
const int inf = 1e18;
int bp(int x, int y, int p){
int res = 1;
x = x % p;
while (y > 0) {
if (y & 1)
res = (res * x) % p;
y = y >> 1;
x = (x * x) % p;
}
return res;
}
int MI(int n, int p){
return bp(n, p - 2, p);
}
int mul(int x,int y, int p){
return x * 1ull * y % p;
}
int di(int x,int y, int p){
return mul(x, MI(y, p), p);
}
int n , m , k , q,d;
void solve(int testcase_number){
cin>>n>>d>>m;
input(int,a,m);
map<int,int>cnt;
vector<pair<int,int>>ord;
for(int i = 0;i<m;i++){
ord.pb({a[i],-(i+1)});
cnt[a[i]]++;
}
int l = 0;
int r = 1e7;
while(r-l>1){
int mi = (l+r)/2;
int day = 1;
int rem = mi;
int f = 1;
for(int i = 1;i<=n;i++){
// if(mi == 1)cout<<i<<" "<<i+d<<" "<<day<<endl;
if(i > day){
day = i;
rem = mi;
}
int x = cnt[i];
int fday = 0;
while(x > 0){
int f1 = min(rem,x);
x-=f1;
rem-=f1;
fday = max(fday,day);
if(rem == 0){
day++;
rem = mi;
}
}
if(fday > i+d){
f = 0;
break;
}
}
if(f){
r = mi;
}
else{
l = mi;
}
}
cout<<r<<endl;
sort(all(ord));
int p1 = 0;
for(int i = 0;i<n;i++){
for(int j = 0;j<r;j++){
if(p1 < (int)ord.size()){
cout<<ord[p1].se*-1<<" ";
p1++;
}
}
cout<<0<<endl;
}
}
signed main(){
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);
cout << fixed<<setprecision(9);
int t = 1;
// cin>>t;
for(int i = 1;i<=t;i++){
solve(i);
}
}
