- h wan ▁as ▁Pil - gy u , ▁polic eman ▁ ▁Lee ▁Young - y oo ▁as ▁Kim ▁Song - yi , ▁J ong - ho ' s ▁daughter ▁Y oon ▁Chan - you ng ▁as ▁So o - ch ul ▁( you ng ) ▁S ung ▁Yu - bin ▁as ▁Fer al ▁boy ▁Kim ▁Bin - wo o ▁as ▁Fem ale ▁victim ▁Se o ▁Hy un - wo o ▁as ▁Pol ic eman ▁Kim ▁Mi - he e ▁as ▁Police w oman ▁Kim ▁Gu - ta ek ▁as ▁Ch oi ▁ ▁References ▁ ▁External ▁links ▁▁▁ ▁Category : S outh ▁Korean ▁thr iller ▁films ▁Category : S outh ▁Korean ▁films ▁Category : S outh ▁Korean ▁serial ▁k iller ▁films ▁Category : 2 0 1 4 ▁films <0x0A> </s> ▁In ▁mathematics , ▁in ▁the ▁study ▁of ▁iter ated ▁functions ▁and ▁dynam ical ▁systems , ▁a ▁periodic ▁point ▁of ▁a ▁function ▁is ▁a ▁point ▁which ▁the ▁system ▁returns ▁to ▁after ▁a ▁certain ▁number ▁of ▁function ▁iterations ▁or ▁a ▁certain ▁amount ▁of ▁time . ▁ ▁Iter ated ▁functions ▁ ▁Given ▁an ▁end omorphism ▁f ▁on ▁a ▁set ▁X ▁ ▁a ▁point ▁x ▁in ▁X ▁is ▁called ▁periodic ▁point ▁if ▁there ▁exists ▁an ▁n ▁so ▁that ▁ ▁where ▁ ▁is ▁the ▁n th ▁iterate ▁of ▁f . ▁The ▁smallest ▁positive ▁integer ▁n ▁satisfying ▁the ▁above ▁is ▁called ▁the ▁prime ▁period ▁or ▁least ▁period ▁of ▁the ▁point ▁x . ▁If ▁every ▁point ▁in ▁X ▁is ▁a ▁periodic ▁point ▁with ▁the ▁same ▁period ▁n , ▁then ▁f