/*
ID: erickca2
TASK: cowdance
LANG: C++
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
// #define int long long
#define endl '\n'
#define pb push_back
#define fs first
#define sc second
#define pii pair<int, int>
const int MAXN = 2*1e5+8;
int N, D, M;
vector<pii> jobs;
bool test(int machines) {
int curr_job = -1;
for(int day = 1; day <= N && curr_job < M; day++) {
for(int j = 0; j < machines; j++) {
curr_job++;
if(curr_job >= M) return true;
int delay = day-jobs[curr_job].fs;
if(delay > D) {
return false;
}
}
}
return true;
}
void find_poss(int machines) {
int curr_job = -1;
for(int day = 1; day <= N; day++) {
if(curr_job >= M) {
cout << 0 << endl;
continue;
}
for(int j = 0; j < machines; j++) {
curr_job++;
if(curr_job >= M) continue;
cout << jobs[curr_job].sc << " ";
}
cout << 0 << endl;
}
return;
}
int32_t main() {
ios_base::sync_with_stdio(NULL); cin.tie(0);
cin >> N >> D >> M;
for(int i = 1; i <= M; i++) {
int x;
cin >> x;
pii j = {x, i};
jobs.pb(j);
}
sort(jobs.begin(), jobs.end());
int l = 1, r = 1e6+8;
int ans = -1;
while(l <= r) {
int mid = l+(r-l)/2;
if(test(mid)) {
ans = mid;
r = mid-1;
} else {
l = mid+1;
}
}
cout << ans << endl;
find_poss(ans);
// cout << ans << endl;
// for(int i = 1; i <= N; i++) {
// for(auto x : poss[i]) {
// cout << x << " ";
// }
// cout << 0 << endl;
// }
}
