Had the same problem. I figured out that it was due to having excess spaces between the answer. Used return str.trim(), and the error was gone.

My bad, I shouldve read the specifications before making the comment lol

Good Point. However, the specification states the function will only be passed two square matrices (N x N).

In your second for loop you shouldnt have also used n, what if the matrices arent square?

Expected: equal to 60212 146017 50473 160148 63092 42537 147424 139514 411638 406581 416904 284633 312489 495225 206947 233992 439822 178485 390984 398994
Actual: 60212 146017 50473 160148 63092 42537 147424 139514 411638 406581 416904 284633 312489 495225 206947 233992 439822 178485 390984 398994
Why isnt this working? My code works for all test cases except random