Fundamental Theorem of calculus

**1. The problem statement, all variables and given/known data**

Find a function *f* : [-1,1] ---> **R** such that f satisfies the following properties:

a) f is continuous

b) f is restricted to (-1,1) is differentiable

c) its derivative f' is not differentiable on (-1,1)

**2. Relevant equations**

**3. The attempt at a solution**

I kinda think that the mean value theorem and Theorem 2 of the fundamentals http://www.physicsforums.com/latex_i.../2144442-0.pngf(x)dx = F(b)-F(a) got some link but I can't seem to get it. I do understand that for f'' not to exist, x should be undefined on the (-1,1). Please help.