How many "words" (actually just letter combinations) can you make with the word SIMILARITIES so that there are no "words" with four consecutive I's.

If am not mistaken the total amount of "words" would be $\displaystyle 12!/(3! \cdot 2!) $

But I don't know how to calculate the amount of words that have four consecutive I's.

I would appreciate if anybody could explain this step by step.

Thank you very much!

PS: I don't really know how to use the math code, but I hope you understand what I wrote.

EDIT: I meant to write 4! as there are 4 I's