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;
using System.Threading.Tasks;
using System.Diagnostics;

static class CodeJam
{
    static int[] Solve(int N, long L, long[] A)
    {
        for (int i = 0; i + 1 < N; ++i)
        {
            if (A[i] + A[i + 1] >= L)
            {
                var ans = new List<int>();
                for (int j = 0; j < i; ++j) { ans.Add(j + 1); }
                for (int j = N - 2; j >= i + 1; --j) { ans.Add(j + 1); }
                ans.Add(i + 1);
                return ans.ToArray();
            }
        }
        return null;
    }

    static void Main(string[] args)
    {
        long[] V = Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
        long[] A = Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
        var ans = Solve((int)V[0], V[1], A);
        if (ans != null)
        {
            Console.WriteLine("Possible");
            foreach (int n in ans) { Console.WriteLine(n); }
        }
        else
        {
            Console.WriteLine("Impossible");
        }
    }
}