need a super cheap mobile for 1k or less.no features needed only long battery life.

hi frnds
i need a super cheap mobile and my budget is 1k or less.
the phone does not need to have any features at all. i only need it to have looooooong battery life. i don't care if it does not even have a color screen,i am ok with black and white or green and black screen also.
this phone is only for making and receiving calls and nothing else(no music no fm) as the person using it does not know how to use them.

so pls help me to find a phone with-
--longest battery life
--slim sleek and small
--not bulky.
thnks