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 PyPy3 (2.4.0) (judge verdict: Accepted)

def examA():
    a, b = LI()
    if a>0:
        ans = "Positive"
        print(ans)
        return
    if b>=0:
        ans = "Zero"
    else:
        judge = b-a
        if judge%2==1:
            ans = "Positive"
        else:
            ans = "Negative"
    print(ans)
    return

def examB():
    N, M = LI()
    boal = [1]*N
    d = defaultdict(bool)
    d[0] = True
    for _ in range(M):
        x,y = LI()
        boal[x-1] -=1
        boal[y-1] +=1
        if d[x-1]:
            d[y-1] = True
        if boal[x-1]==0:
            d[x-1] = False
    ans = sum(d.values())
    print(ans)
    return

def examC():
    N, L = LI()
    A = LI(); cur = -1
    ans = "Impossible"
    for i in range(N-1):
        if A[i]+A[i+1]>=L:
            ans = "Possible"
            cur = i
            break
    print(ans)
    if cur==-1:
        return
    ansC = []
    for i in range(cur):
        ansC.append(i)
    for i in range(N-2,cur,-1):
        ansC.append(i)
    ansC.append(cur)
    for v in ansC:
        print(v+1)
    return

import sys,copy,bisect,itertools,heapq,math
from heapq import heappop,heappush,heapify
from collections import Counter,defaultdict,deque
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))
def LSI(): return list(map(str,sys.stdin.readline().split()))
def LS(): return sys.stdin.readline().split()
def SI(): return sys.stdin.readline().strip()
mod = 10**9 + 7
inf = float('inf')

if __name__ == '__main__':
    examC()