#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define pii pair<ll, ll>
#define fi first
#define se second
const ll N = 2e5 + 5, inf = 1e18, mod = 1e9 + 7, block = 320, lim = 1 << 16;
int n, d, m;
int a[N];
vector <int> days[N];
vector <pii> comp;
bool check(int mid) {
for (int i = 1; i <= n; i++) days[i].clear();
int p = 0;
bool check = true;
for (int i = 1; i <= n; i++) {
int x = mid;
while(x > 0 && p < m) {
days[i].push_back(comp[p].se);
if (i - d > comp[p].fi) {
check = false;
break;
}
p++;
x--;
}
if (!check) break;
days[i].push_back(0);
}
return check;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> d >> m;
for (int i = 1; i <= m; i++) {
cin >> a[i];
comp.emplace_back(a[i], i);
}
// sort(a + 1, a + m + 1);
sort(comp.begin(), comp.end());
// for (int i = 1; i <= m; i++) cout << a[i] << ' ';
cout << '\n';
int l = 1, r = 1e9, ans = 0;
while(l <= r) {
int mid = (l + r) / 2;
if (check(mid)) {
ans = mid;
r = mid - 1;
}
else l = mid + 1;
}
cout << ans << '\n';
for (int i = 1; i <= n; i++) {
for (auto v : days[i]) cout << v << ' ';
cout << '\n';
}
return 0;
}
