#include<bits/stdc++.h>
[[maybe_unused]] typedef long long ll;
[[maybe_unused]] const int N = (int) 1e6 + 20;
[[maybe_unused]] const int mod = (int) 1e9 + 7;
[[maybe_unused]] char endl = '\n';
[[maybe_unused]] char space = ' ';
[[maybe_unused]] const int off = 1 << 18;
void Run();
int main()
{
Run();
//in
int t = 1;
// std::cin >> t;
while (t--) {
int n,d,m;
std::cin >> n >> d >> m;
std::set<std::pair<int,int>,std::greater<>> s;
for (int i = 1; i <= m; ++i) {
int x;
std::cin >> x;
s.insert({x,i});
}
//ops
std::vector<std::queue<int>> days(n + 1);
std::vector<int> rm(m,n + 1);//pos of rightmost day wth i as num of jobs
for (const auto &[u,v]: s) {
int low = int(std::lower_bound(rm.begin(), rm.end(),u) - rm.begin());
rm[low] = std::min(rm[low], u + d);
days[rm[low]--].push(v);
if (rm[low + 1] == n + 1) {
rm[low + 1] = rm[low] + 1;
}
}
//out
int max = INT_MIN;
for (const auto &item: days) {
max = std::max((int)item.size(),max);
}
std::cout << max << endl;
for (int i = 1; i <= n; ++i) {
while(!days[i].empty()) {
std::cout << days[i].front() << space;
days[i].pop();
}
std::cout << 0;
if (i != n) {
std::cout << endl;
}
}
}
return 0;
}
void Run(){
std::ios_base::sync_with_stdio(false);std::cin.tie(nullptr);std::cout.tie(nullptr);
#ifndef ONLINE_JUDGE
// freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
#endif
}
