#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 7;
int n, d, m;
int f[N];
vector <int> g[N];
bool check(int t) {
deque < pair <int, int> > h;
for(int i = 1; i <= n; i++) {
if(f[i]) h.emplace_back(i, f[i]);
int cur_t = t;
while(!h.empty() && cur_t) {
if(i - h[0].first > d) return false;
int next_t = cur_t;
next_t -= min(h[0].second, cur_t);
h[0].second -= min(h[0].second, cur_t);
cur_t = next_t;
if(h[0].second == 0) {
h.pop_front();
}
}
}
if(h.size()) return false;
return true;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> d >> m;
for(int i = 0; i < m; i++) {
int x;
cin >> x;
f[x]++;
g[x].push_back(i + 1);
}
int low = 1, high = m, best = m;
while(low <= high) {
int mid = (low + high) >> 1;
if(check(mid)) {
best = mid;
high = mid - 1;
} else {
low = mid + 1;
}
}
cout << best << '\n';
deque < pair <int, int> > h;
for(int i = 1; i <= n; i++) {
if(f[i]) h.emplace_back(i, f[i]);
int cur_t = best;
while(!h.empty() && cur_t) {
int next_t = cur_t;
for(int j = 0; j < min(h[0].second, cur_t); j++) {
cout << g[h[0].first].back() << ' ';
g[h[0].first].pop_back();
}
next_t -= min(h[0].second, cur_t);
h[0].second -= min(h[0].second, cur_t);
cur_t = next_t;
if(h[0].second == 0) {
h.pop_front();
}
}
cout << "0\n";
}
return 0;
}
