Grammar still ambigous after removing left recursion LL(1)


I have following grammar it doesnt not have Epsilon-derivation problem I can only see left recursion:

S -> a b S S -> S a b  S -> c d S -> a d 

in production number 2 there is left recursion which I removed and I got:

S -> a b S F S -> c d F S -> a d F F -> a b F | EPSILON 

But it is still ambigous?