#include <bits/stdc++.h>
// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #define int long long
#define ld long double
#define ll long long
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
using namespace std;
const int oo = 1e9 + 9;
const int MAX = 1e6 + 5, LOGMAX = 20, B = 441, MOD = 998244353;
int n, d, m;
vector<int> E[MAX];
bool check(int mid, bool ans = 0){
vector<int> vis(m + 1, 0);
queue<int> cur;
bool bl = 1;
for(int i = 1; i <= n + 1; i++){
for(int a : E[i]){
if(a > 0) cur.push(a);
else if(!vis[-a]) bl = 0;
}
int a = mid;
while(a-- && cur.size()){
if(ans) cout << cur.front() << ' ';
vis[cur.front()] = 1;
cur.pop();
}
if(ans && i != n + 1) cout << "0\n";
}
return bl;
}
void solve(){
cin >> n >> d >> m;
for(int i = 1; i <= m; i++){
int a; cin >> a;
E[a].push_back(i);
E[a + d + 1].push_back(-i);
}
int l = 1, r = m;
while(l < r){
int mid = (l + r) / 2;
if(check(mid)) r = mid;
else l = mid + 1;
}
cout << l << '\n';
check(l, 1);
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
}
