DiskTower

import java.io.*;
import java.util.*;
public class DiskTower {
    public static void main(String[] args) throws IOException{
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(in.readLine());
        PriorityQueue<Integer> q = new PriorityQueue<Integer>(n, Collections.reverseOrder());
        StringTokenizer st = new StringTokenizer(in.readLine());

        int next = n;
        for(int i = 0; i < n; i ++) {
            int d = Integer.parseInt(st.nextToken());
            q.offer(d);
            while(!q.isEmpty() && q.peek() == next) {
                System.out.print(q.poll() + " ");
                next --;
            }
            System.out.println();
        }
    }
}