#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
template<typename T> bool ckmin(T &a, T b){return (b < a) ? a = b, 1 : 0;}
template<typename T> bool ckmax(T &a, T b){return (b > a) ? a = b, 1 : 0;}
const char el = '\n';
void solve() {
int n, d, m;
cin >> n >> d >> m;
vector<pair<int, int>> a(m);
for (int i = 0; i < m; ++i) {
cin >> a[i].first;
a[i].second = i + 1;
}
int l = 0, r = m;
sort(all(a));
int ans = (int) 1e18;
while (l <= r) {
int mid = (l + r) >> 1LL;
bool ok = true;
for (int i = 1, j = 0; i <= n && j < m; ++i) {
int cnt = 0;
while (j < m && cnt < mid && a[j].first <= i && a[j].first + d >= i) {
++cnt;
++j;
}
if (j < m && a[j].first + d < i) {
ok = false;
break;
}
}
if (ok) {
ckmin(ans, mid);
r = mid - 1;
} else l = mid + 1;
}
cout << ans << el;
for (int i = 1, j = 0; i <= n; ++i) {
int cnt = 0;
while (j < m && cnt < ans && a[j].first <= i && a[j].first + d >= i) {
cout << a[j].second << " ";
++cnt;
++j;
}
cout << "0\n";
}
}
signed main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int testcase = 1; /// cin >> testcase;
while (testcase--) {
solve();
}
return 0;
}
