As anyone who knows about different alphabets could tell you, just because a Cyrillic character happens to bear a (coincidental) resemblance to a Latin one, that doesn't mean that they are equivalent; Cyrillic is based on Greek, not Latin.
For instance, Р is called "rtsui" and hence in Latin terms is an R, not the P it superficially resembles. Likewise, и is "ishe" and thus an I, and й is "ishe breve" ("short Cyrillic i") and thus an ï.
Do some research next time (e.g. Wikipedia or Google) before spouting off on a subject you clearly know nothing about.