On a blackboard , the 2016 numbers $\frac{1}{2016} , \frac{2}{2016} ,... \frac{2016}{2016}$ are written.
One can perfurm the following operation : Choose any numbers in the blackboard, say $a$ and$ b$ and replace them by $2ab-a-b+1$.
After doing 2015 operation , there will only be one number $t$ Onthe blackboard .
Find all possible values of $ t$.