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 <bits/stdc++.h>
using namespace std;

#define f(i,a,b) for (int i = a; i < b; i++)

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int n, k;
	cin >> n >> k;
	int a[n];
	f(i,0,n) cin>>a[i];
	stringstream ss;
	ss << "Impossible" << endl;
	f(i,0,n-1) {
		if (a[i] + a[i+1] >= k) {
			ss = stringstream();
			ss << "Possible" << endl;
			f(j,0,i) ss << j+1 << endl;
			f(j,i+1,n-1) ss << j+1 << endl;
			ss << i+1 << endl;
			break;
		}		
	}
	cout << ss.str();
	return 0;
}