actualli there's 100% say dat is e "safe priod".depend on
individual.but normall,the 3 days b4 ur period and 3 days after ur
period,can consider as "safe period". so ur period muz those always
cum on time 1 then can count safe period.
tis wat i noe.
wanna a safe sex,eat pill loh.then really can enjoy wifout
"umbrella" 
