import math
from collections import deque
def mindef(josh,lent,f):
    defence=0
    pos=0
    lent=len(bc)
    if josh%2==0:
        pos=lent-1
    else:
        defence+=a[josh-1]
        pos=lent-1
    if lent&(lent-1)==0:
        return defence
    mult=1
    while lent>1:
        if lent%2==0:
            if lent and (not(lent&(lent-1))):
                return defence
        if lent%2==0:
            pos-=mult
            lent=lent//2
        else:
            defence+=bc[pos]
            lent=lent//2+1
        mult*=2
    return defence
t=int(input())
for qwe in range(t):
    n=int(input())
    n=n-1
    a=list(map(int,input().split(" ")))
    bc=deque(a)
    f=int(input())
    pos_=-1
    deff=10**9+7
    for i in range(0,n):
        if i==0:
            None
        elif i%2==1:
            x=bc.popleft()
            bc.append(x)
        else:
            bc.popleft()
        if bc[0]<=f:
            if i%2==0:
                number=n-i//2
                if number and (not(number&(number-1))):
                    deff=0
                    pos_=i
                    break
            mina=mindef(i,n,f)
            if mina<deff:
                deff=mina
                pos_=i
                if deff==0:
                    break
    if deff==10**9+7:
        print("impossible")
    else:
        print("possible")
        print(pos_+1,deff+f)