// Born_To_Laugh - Hughie Do
#include <bits/stdc++.h>
#define alle(AC) AC.begin(), AC.end()
#define fi first
#define se second
using namespace std;
typedef long long ll;
[[maybe_unused]] const int MOD = 998244353, INF = 1e9 + 7;
const int maxn = 1e5 + 10;
int n, d, m;
vector<int> job[maxn];
int tim[int(1e6) + 5];
bool check(int num){
deque<int> dq;
for(int i=1; i<=n; ++i){
for(auto &elm: job[i]) dq.push_back(elm);
for(int j=1; j<=num; ++j){
if(dq.empty()) break;
if(tim[dq.front()] + d < i) return 0;
dq.pop_front();
}
}
return 1;
}
void solve(){
cin >> n >> d >> m;
for(int i=1; i<=m; ++i){
cin >> tim[i];
job[tim[i]].push_back(i);
}
int lo = 1, hi = m;
int res = hi;
while(hi >= lo){
int mid = (lo + hi) >> 1;
if(check(mid)){
res = mid;
hi = mid - 1;
}
else lo = mid + 1;
}
cout << res << '\n';
deque<int> dq;
for(int i=1; i<=n; ++i){
for(auto &elm: job[i]) dq.push_back(elm);
for(int j=1; j<=res; ++j){
if(dq.empty()) break;
cout << dq.front() << ' ';
dq.pop_front();
}
cout << 0 << '\n';
}
}
signed main(){
// freopen("inp.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
}
