#include <iostream>
#include <iomanip>
#include <fstream>
#include <vector>
#include <array>
#include <algorithm>
#include <utility>
#include <map>
#include <queue>
#include <set>
#include <cmath>
#include <cstdio>
#include <cstring>
#define ll long long
#define ld long double
#define eps 1e-8
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFLL 0x3f3f3f3f3f3f3f3f
// change if necessary
#define MAXN 1000010
using namespace std;
int n;
pair<int, int> players[MAXN];
// {num_teams, max_size, cur_size}
array<int, 3> dp[MAXN];
void cmp(array<int, 3> &a, const array<int, 3> &b) {
if (a[0] == b[0]) {
a = min(a, b);
} else {
a = max(a, b);
}
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 0; i < n; i++) {
cin >> players[i].first;
players[i].second = i;
}
sort(players, players + n, greater<pair<int, int>>());
for (int i = 0; i <= n; i++) {
dp[i] = {-1, 0};
}
dp[players[0].first] = {1, players[0].first, players[0].first};
for (int i = 0; i < n; i++) {
if (dp[i][0] != -1) {
if (i == dp[i][0] * dp[i][1]) {
cmp(dp[i + 1], {dp[i][0], dp[i][1] + 1, 0});
} else {
cmp(dp[i + 1], {dp[i][0], dp[i][1], 0});
}
if (i + players[i].first <= n) {
cmp(dp[i + players[i].first], {dp[i][0] + 1, max(dp[i][1], players[i].first), players[i].first});
}
}
}
set<int> to_assign;
vector<vector<int>> ans;
int cur = n;
while (cur > 0) {
int nxt_cur = cur - dp[cur][2];
if (nxt_cur == cur) {
to_assign.insert(cur - 1);
cur--;
} else {
ans.push_back({});
for (int i = nxt_cur; i < cur; i++) {
ans.back().push_back(players[i].second);
}
cur = nxt_cur;
}
}
int idx = dp[n][0] - 1;
for (int i : to_assign) {
while ((int)(ans[idx].size()) == dp[n][1]) {
idx--;
}
ans[idx].push_back(players[i].second);
}
cout << dp[n][0] << '\n';
for (auto &v : ans) {
cout << v.size() << ' ';
for (int i : v) cout << i + 1 << ' ';
cout << '\n';
}
return 0;
}
