Questions about Griewank function and its starting point and global minimum

I have a questions regarding Griewank functions..I was asked to use Newton's method to find the minimum of griewank function with the starting point of (-2,2)

Griewank function:

f(x,y) = (x^2+y^2)/4000 -cos(x)*cos(y/sqrt(2)) + 1

but my answer is (-1.57,2.22)

since the global minimum of Griewank function is known to be (0,0)

why the starting point (-2,2) does not lead to (0,0)? why is it (-1.57,2.22)?

what had stops to find the global minimum?