Problem:
Score : 400 points

Problem Statement

Snuke has an empty sequence a.

He will perform N operations on this sequence.

In the i-th operation, he chooses an integer j satisfying 1 \leq j \leq i, and insert j at position j in a (the beginning is position 1).

You are given a sequence b of length N. Determine if it is possible that a is equal to b after N operations. If it is, show one possible sequence of operations that achieves it.

Constraints

All values in input are integers.

1 \leq N \leq 100

1 \leq b_i \leq N

Input

Input is given from Standard Input in the following format:

N
b_1 \dots b_N

Output

If there is no sequence of N operations after which a would be equal to b, print -1.
If there is, print N lines. In the i-th line, the integer chosen in the i-th operation should be printed. If there are multiple solutions, any of them is accepted.

Sample Input 1

3
1 2 1

Sample Output 1

1
1
2

In this sequence of operations, the sequence a changes as follows:

After the first operation: (1)

After the second operation: (1,1)

After the third operation: (1,2,1)

Sample Input 2

2
2 2

Sample Output 2

-1

2 cannot be inserted at the beginning of the sequence, so this is impossible.

Sample Input 3

9
1 1 1 2 2 1 2 3 2

Sample Output 3

1
2
2
3
1
2
2
1
1

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;
import java.util.stream.Collectors;

public class Main {

    public static void main(String[] args) {
        // TODO code application logic here
        Scanner sc = new Scanner(System.in);
//        String str = sc.nextLine();
        int count = sc.nextInt();
        boolean flag=true;
        List<Integer> data = new ArrayList<>();
        for (int i = 1; i <= count; i++) {
            data.add(sc.nextInt());
        }
        List<Integer> sorted = data.stream().collect(Collectors.toList());
        sorted.sort(Comparator.naturalOrder());
        int j=1;
        while (flag) {
            if(!sorted.isEmpty()){
                for (int i = 1; i <= j; i++) {
    //                System.out.println(sorted.indexOf(i));
                    if (sorted.indexOf(i)!=-1){
                        System.out.println(sorted.get(sorted.indexOf(i)));
                        sorted.remove(sorted.indexOf(i));
                        break;
                    }
                    if(i==j){
                        System.out.println("-1");
                        flag=false;
                        break;
                    }
                }
                j++;
            }else
                flag=false;
        }
    }
}