Hello Codeforcians!
I would like to know if there is an efficient method to calculate
where $$$k = N-(A+B+O+R)$$$ (of course all k's are greater than or equal zero), the output is modulo $$$1'000'000'007$$$, and $$$0\leq A,B,O,R, N\leq 400,000$$$. The time limit was 2 seconds, however any suggestions are more than welcome.
Thank you!