#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update>
#define endl '\n'
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int n, d, m;
cin >> n >> d >> m;
vector<vector<int>> job(n + 1);
for (int i = 1; i <= m; i++) {
int start;
cin >> start;
job[start].push_back(i);
}
vector<vector<int>> ans;
int ll = 0, rr = m;
while (ll < rr) {
int mm = (ll + rr) / 2;
vector<vector<int>> tans(n + 1);
queue<pair<int, int>> in_process;
for (int i = 1; i <= n; i++) {
for (int j : job[i])
in_process.push({j, i + d});
for (int j = 0; j < mm; j++) {
if (in_process.size() == 0) break;
auto tmp = in_process.front();
if (tmp.second < i) break;
tans[i].push_back(tmp.first);
in_process.pop();
}
}
if (in_process.size() > 0)
ll = mm + 1;
else {
rr = mm;
ans = tans;
}
}
cout << rr << endl;
for (int i = 1; i <= n; i++) {
for (int j : ans[i])
cout << j << ' ';
cout << 0 << endl;
}
return 0;
}
