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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <vector>
#include <cstdio>
using namespace std;
int s,n,m;
int a[300000];
int main() {
    ios_base::sync_with_stdio(0);
    cin >> n >> m;
    for (int i=1;i<=n;i++) cin >> a[i];
    int mx=-1;
    int nm=0;
    for (int i=1;i<n;i++)
    if (a[i]+a[i+1]>mx) {
        mx=a[i]+a[i+1];
        nm=i;
    }
    if (mx<m) cout << "Impossible\n";
    else {
        cout << "Possible\n";
        for (int i=1;i<nm;i++) cout << i << "\n";
        for (int i=nm+1;i<n;i++) cout << i << "\n";
        cout << nm << "\n";
    }
    return 0;
}