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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.util.stream.*;
import java.io.*;

public class Main {
    
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] in1 = br.readLine().split(" ");
        int N = Integer.parseInt(in1[0]);
        int L = Integer.parseInt(in1[1]);
        
        in1 = br.readLine().split(" ");
        int[] a = Stream.of(in1).mapToInt(Integer::parseInt).toArray();
        br.close();

        int last_cut_rope_idx = 0;
        for(int i = 0; i < N-1; i++){
            if(a[i] + a[i+1] >= L) {
                last_cut_rope_idx = i + 1;
            }
        }

        System.out.println(last_cut_rope_idx != 0 ? "Possible" : "Impossible");
        
        if(last_cut_rope_idx != 0){
            int cut_rope = 1;
            while(cut_rope != last_cut_rope_idx){
                System.out.println(cut_rope);
                cut_rope++;
            }

            cut_rope = N - 1;
            while(cut_rope != last_cut_rope_idx){
                System.out.println(cut_rope);
                cut_rope--;
            }
        
            System.out.println(last_cut_rope_idx);
        }
    }
}