for t in xrange(int(raw_input())):
r = int(raw_input())
r = r - 1
array = map(int, raw_input().split())
flag = 0
result = 1
array.sort()
while r >= 0:
if array[r] <= r:
flag = 1
break
result = (result * (array[r] - r)) % 1000000007
r -= 1
if flag:
print "0"
else:
print result
print "KILL BATMAN"
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