You have the `radius` of a circle with the center in point `(0,0)`.
Write a function that calculates the number of points in the circle where `(x,y)` - the cartesian coordinates of the points - are `integers`.
Example: for `radius = 2` the result should be `13`.
`0 <= radius <= 1000`
![](http://i.imgur.com/1SMov3s.png)
def points(radius):
    cnt = radius * 4 + 1
    r2 = radius * radius
    for i in range(1, radius + 1):
        for j in range(1, radius + 1):
            if (i * i + j * j <= r2):
                cnt += 4
    return cnt


def points(radius):
    cnt = radius * 4 + 1
    r2 = radius * radius
    for i in range(1, radius + 1):
        for j in range(1, radius + 1):
            if (i * i + j * j <= r2):
                cnt += 4
    return cnt

