#include <bits/stdc++.h>
using namespace std;
using ll = long long;
bool cmp(const vector<ll>& a, const vector<ll>& b)
{
return a[0] < b[0];
}
int main()
{
ll n, d, m;
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> d >> m;
vector<vector<ll>> jobs(m);
for (ll i = 1; i <= m; ++i) {
ll a;
cin >> a;
jobs[i - 1] = {a, i};
}
sort(jobs.begin(), jobs.end(), cmp);
vector<vector<ll>> ans;
ll l = 1, r = m;
while (l < r) {
ll mid = l + (r - l) / 2, start = 0;
//cout << "testing mid: " << mid << "\n";
//bool check = true;
vector<vector<ll>> jobstmp(n);
for (ll i = 0; i < n; ++i) {
//cout << "a\n";
for (ll j = 0; j < mid && start <= m - 1; ++j) {
//cout << "bat\n";
if (jobs[start][0] <= i + 1) {
jobstmp[i].push_back(jobs[start][1]);
++start;
//cout << "at\n";
}
else {
break;
}
}
//cout << "heree\n";
jobstmp[i].push_back(0);
//cout << "h\n";
}
/*for (auto val : jobstmp) {
for (ll i : val) {
cout << i << " ";
}
cout << "\n";
}*/
//cout << "start: " << start << " check: " << "\n";
if (start == m) {
//cout << "r from " << r << " to r -> " << mid << "\n";
r = mid;
ans = jobstmp;
}
else {
//cout << "l from " << l << " to l -> " << mid << " + 1\n";
l = mid + 1;
}
}
cout << l << "\n";
for (auto i : ans) {
for (ll j : i) {
cout << j << " ";
}
cout << "\n";
}
}
