#include <bits/stdc++.h>
#define ll long long
#define FOR(x, n) for(int x = 0; x < n; x++)
#define LFOR(x, l, r) for(int x = l; x < r; x++)
#define last(x) x[x.size()-1]
#define negind(x, i) x[x.size()-i]
#define pii pair<int, int>
#define ins insert
#define pb push_back
#define pf push_front
#define s(x) set(x)
#define v(x) vector<x>
#define uom(x, y) unordered_map<x, y>
#define triplet(x) tuple<x, x, x>
#define all(x) x.begin(), x.end()
#define inf INT_MAX
using namespace std;
inline void solve(){
int N, D, M;
cin >> N >> D >> M;
pii a[M];
FOR(i, M){
cin >> a[i].first;
a[i].second = i+1;
}
sort(a, a+M);
int l = 1, r = 1000000, sol;
while(l <= r){
int mid = l + (r-l)/2, index = mid-1, day = 1, delay = 0;
while(index < M){
delay = max(delay, day-a[index].first);
day++;
FOR(i, mid){
if(index >= M || a[index+1].first > day) break;
index++;
}
}
if(delay <= D) sol = mid, r = mid - 1;
else l = mid+1;
}
cout << sol << endl;
int index = 0;
while(index < M){
LFOR(i, index, min(M, index+sol)) cout << a[i].second << " ";
index += sol;
cout << "0\n";
}
FOR(i, N-ceil((double)M/sol)) cout << "0\n";
}
int main() {
cin.tie(0);
ios::sync_with_stdio(0);
solve();
return 0;
}
