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 Python (3.4.3) (judge verdict: Wrong Answer)

n=int(input())
d=list(map(int,input().split()))
b=sorted([[i+1,h] for i,h in enumerate(d)],key=lambda x:(x[1],x[0]))
c=[]
for i in range(n-1,-1,-1):
    if 0<b[i][1]<=i+1 and 0<b[i][0]<=i+1:
        c.append(b[i][1])
        d.pop(b[i][0]-1)
        b=sorted([[i+1,h] for i,h in enumerate(d)],key=lambda x:(x[1],x[0]))
    else:
        print(-1)
        break
else:
    for i in c[::-1]:
        print(i)