Your solution should work with long and int as indicated in the initial solution public static long checkchoose(long m, int n). No need for BigInteger in this kata. Note that checkchoose is not choose. Maybe you could read again the description:-)

Oops. Sorry about that. I am working this Kata in Java.

Please whih language?

Help requested. My solution seems to be choking primative primitive int limitations, as evidenced by the following:
30 choose 11 equals 54627300; m equals 155117520
30 choose 12 equals 86493225; m equals 155117520
30 choose 13 equals 119759850; m equals 155117520
30 choose 14 equals -66175233; m equals 155117520
That said, I've tried very hard to make my program always use a primitive long type at all stages. I could convert to BigInteger, and that would likely solve the problem, but I am trying to learn about long vs. int and what I am doing wrong. (Should I paste my code here?)

okay. I was way off in my interpretation of the requirements, as it turns out, and the hyphen was just the "character" to point that out. thanks.

Underscore is valid, hyphen is not.

I have a question about testInvalid4(IdentifierCheckerTest)
The string being passed in appears to be "str-str"
The expected result is Invalid
Per my reading of the requirements, I would expect the expected result to be Valid
-> each item in the string "s" "t" "r" "-" appears to be valid, at least based on my understanding
So, why is the expected result Invalid?