1.
The number of points where the function f:R→Rf: \mathbb{R} \to \mathbb{R},
f(x)=∣x−1∣(cos⁡2x+2sin⁡x−1)+(x−3)∣x2−5x+4∣f(x) = |x-1|(\cos^2 x + 2\sin x - 1) + (x-3)|x^2 - 5x + 4|
is NOT differentiable, is