The puzzle:

The string "my_id" is nine characters long, three English letters followed by six digits. There are three parts to the puzzle that you must solve.

Part One:

In the paragraph below, find the three letters with the fewest occurrences. List the three letters in order, beginning with the one that is most rare. These are the first three characters of "my_id".

SZADLTFOLNRCHUXDBDCALCCDCBVNMAKLCAOBBFGUM

XMAABEINABAQBAOBAZBXAVBKCUDYHCYCQCDOCYNXE

RFMCGCUVYJABPIHQWYHALOBKABAPXSMIBAJZYVBQA

HUZBABKAGJBFOPXQIQSCDRCVCHGABJCKASDFMPRBA

UBIWASLGWEBABJAWCRPZHBWVDKCAZWAIFRGPSAJAT

Part Two:

The second three characters of "my_id" are "362"

Part Three:

Subtract 999 from the year in which Albert Einstein was born. The resulting number represents the last three characters of "my_id".

Alternate puzzle:

If you are good at math, here’s a faster way to solve the puzzle: The solution is an integer N spelled out in English (for example, three if N=3) followed by number of ways in which N distinct objects can be arranged relative to each other in a circle. So for N=3, the solution would be "three2", since objects A, B, and C can be arranged either as ABC or BAC, since CAB and BCA are each equal to ABC, while ACB and CBA are each equal to BAC.