#include <bits/stdc++.h>
using namespace std;
#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ll long long
struct P{
ll x, y;
};
void dbg_out() { cerr << endl; }
template <typename H, typename... T>
void dbg_out(H h, T... t) { cerr << ' ' << h; dbg_out(t...); }
#define dbg(...) { cerr << #__VA_ARGS__ << ':'; dbg_out(__VA_ARGS__); }
signed main(){
fastio;
int n, d, m;
cin >> n >> d >> m;
vector<pair<int, int>> arr (m);
for (int i=1, x; i<=m; i++){
cin >> x;
arr[i-1] = {x, i};
}
sort(all(arr));
int pcs=1;
for (int i=0; i<m; i++){
while ((i+pcs)/pcs > arr[i].first+d) pcs++;
}
cout << pcs << '\n';
int j=0;
for (int i=0; i<n; i++){
for (int k=0; k<pcs && j<m; k++, j++){
cout << arr[j].second << ' ';
}
cout << 0 << '\n';
}
}
