i formatted the hard disk from windows, the mac work with windows only and i cant find os x boot, how can i install it again please help.

i used bootcamp to install windows on mac after that when installing windows it asked me to format the bootcamp drive but it couldn't continue I formatted the full hard disk by clicking ( fn-shift-f10) and clean the hard disk after that the mac work with windows only and partition of mac os x is terminated or deleted I need to install it again.