Sir , I thought since this is online, the question asked would not be cleared.But I was wrong ,you made it so clear for me.Thank you so much.
Hello
We need to find k where
k < c - 1/2
Assume c = 1
k < 1 - 1/2
k < 1/2
So, if we take
k = c - 1
k = 1 - 1
k = 0
Then, k < c -1/2
That is why we take
k = c - 1