Problem:
Problem Statement

We have N pieces of ropes, numbered 1 through N. The length of piece i is a_i.

At first, for each i (1≤i≤N-1), piece i and piece i+1 are tied at the ends, forming one long rope with N-1 knots. Snuke will try to untie all of the knots by performing the following operation repeatedly:

Choose a (connected) rope with a total length of at least L, then untie one of its knots.

Is it possible to untie all of the N-1 knots by properly applying this operation? If the answer is positive, find one possible order to untie the knots.

Constraints

2≤N≤10^5

1≤L≤10^9

1≤a_i≤10^9

All input values are integers.

Input

The input is given from Standard Input in the following format:

N L
a_1 a_2 ... a_n

Output

If it is not possible to untie all of the N-1 knots, print Impossible.

If it is possible to untie all of the knots, print Possible, then print another N-1 lines that describe a possible order to untie the knots. The j-th of those N-1 lines should contain the index of the knot that is untied in the j-th operation. Here, the index of the knot connecting piece i and piece i+1 is i.

If there is more than one solution, output any.

Sample Input 1

3 50
30 20 10

Sample Output 1

Possible
2
1

If the knot 1 is untied first, the knot 2 will become impossible to untie.

Sample Input 2

2 21
10 10

Sample Output 2

Impossible

Sample Input 3

5 50
10 20 30 40 50

Sample Output 3

Possible
1
2
3
4

Another example of a possible solution is 3, 4, 1, 2.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class GFG
{
    static public void Main()
    {
        try
        {

            var input1 = Console.ReadLine().Split(' ');
            var n = int.Parse(input1[0]);
            var L = int.Parse(input1[1]);

            var aar = Console.ReadLine().Split(' ').Select(x => Int32.Parse(x)).ToArray();

            KnotPuzzle(n, L, aar);
        }
        catch (Exception ex)
        {
            Console.Write(ex);
        }
    }

    static void KnotPuzzle(int n, int L, int[] arr)
    {

        int index = 0;

        for (int i = 1; i < n; i++)
        {
            if (arr[i] + arr[i - 1] >= L)
            {
                index = i;
                break;
            }
        }

        if (index > 0)
        {

            Console.Write("Possible");
            Console.WriteLine();
            for (int k = 1; k < index; k++)
            {
                Console.Write(k);
                Console.WriteLine();
            }
            for (int k = n - 1; k >= index; k--)
            {
                Console.Write(k);
                Console.WriteLine();
            }
        }
        else
        {
            Console.Write("Impossible");
        }

    }

}