#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;
vector<vector<int> > poss;
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;
poss.resize(N+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;
poss[day].pb(jobs[curr_job].sc);
// cout << day << ": " << jobs[curr_job].sc << 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;
}
}
find_poss(ans);
cout << ans << endl;
for(int i = 1; i <= N; i++) {
for(auto x : poss[i]) {
cout << x << " ";
}
cout << 0 << endl;
}
}
