searching a value of a dict (each value is a list)

[Seongsu Lee]

Hi,

I have a dictionary with million keys. Each value in the
dictionary has a list with up to thousand integers.
Follow is a simple example with 5 keys.

dict = {1: [1, 2, 3, 4, 5],
   2: [10, 11, 12],
   900000: [100, 101, 102, 103, 104, 105],
   900001: [20, 21, 22],
   999999: [15, 16, 17, 18, 19]}

I want to find out the key value which has a specific
integer in the list of its value. For example, if I search
104 in the list, 900000 must be returned.

How can I do this with Python? Ideas?