#include <bits/stdc++.h>
#define DIM 1000010
#define INF 2000000000
using namespace std;
pair <int,int> dp[DIM],v[DIM];
vector <int> sol[DIM],events[DIM];
vector <pair<int,int> > s;
int t[DIM],p[DIM],rmq[30][DIM];
int n,i,j,k,maxim;
int get_max (int x, int y){
int nr = p[y-x+1];
return max (rmq[nr][x],rmq[nr][y-(1<<nr)+1]);
}
int main (){
//ifstream cin ("date.in");
//ofstream cout ("date.out");
cin>>n;
for (i=1;i<=n;i++){
cin>>v[i].first;
v[i].second = i;
}
sort (v+1,v+n+1);
reverse (v+1,v+n+1);
for (i=1;i<=n;i++)
rmq[0][i] = v[i].first;
for (i=1;(1<<i)<=n;i++)
for (j=1;j<=n;j++){
rmq[i][j] = rmq[i-1][j];
if (j + (1<<(i-1)) <= n && rmq[i-1][j + (1<<(i-1))] > rmq[i][j])
rmq[i][j] = rmq[i-1][j + (1<<(i-1))];
}
for (i=2;i<=n;i++)
p[i] = p[i/2] + 1;
/// dp[i] - nr maxim de secv in care pot imparti sirul si care e dimensiunea maxima minima
for (i=1;i<=n;i++)
dp[i] = make_pair(-INF,INF);
/// cand incepe sa aiba influenta un dp?
for (i=1;i<=n;i++){
/*int st = i, dr = n, sol = 0;
while (st <= dr){
int mid = (st+dr)>>1;
if (v[i].first <= mid-i+1){
sol = mid;
dr = mid-1;
} else st = mid+1;
}*/
events[i + v[i].first - 1].push_back(i-1);
}
int maxim = -1;
for (i=1;i<=n;i++){
for (auto it : events[i]){
if (dp[it].first > maxim){
maxim = dp[it].first;
s.clear();
s.push_back(make_pair(dp[it].second,it));
} else {
if (dp[it].first == maxim)
s.push_back(make_pair(dp[it].second,it));
}
}
if (maxim == -1)
continue;
/// calculez dp[i];
dp[i].first = maxim + 1;
for (auto it : s){
if (max(it.first,i-it.second) < dp[i].second){
dp[i].second = max(it.first,i-it.second);
t[i] = it.second;
}
}
}
int x = n;
while (x > 0){
++k;
for (i=t[x]+1;i<=x;i++)
sol[k].push_back(v[i].second);
x = t[x];
}
cout<<k<<"\n";
for (i=1;i<=k;i++){
cout<<sol[i].size()<<" ";
for (auto it : sol[i])
cout<<it<<" ";
cout<<"\n";
}
return 0;
}
