To ask something if during menstruation is safe having sex and after the menstruation how many days would be safe?

You can safely: Have intercourse during menstruation. It's more so a hygienic concern that people have that leads to the avoidance of sex during menstruation. Though, if you have a blood borne illness, it may place your significant other at greater risk of being infected just related to being exposed to a obvious blood.

NeedHigherCalculus: With the proviso that you can get pregnant any time--during your period is a low risk time. Think of it like this, the probability is lowest at the beginning (or a little before)the start of your period and then increases progressively each day until ovulation when it is highest (starting a few days before ovulation) then decreases near the next cycle. Confusing? Good. ALWAYS USE PROTECTION.