# Sqrt(x)
# Do not use build in operator


class Solution:
    def mySqrt(self, c: int) -> int:
        # Use Newton's method, return the smaller root
        # fx = x ** 2 - c
        # Xn-1 = 0.5 * (Xn + c / Xn)
        x = c / 2
        while True:
            next_x = (x + c / x) / 2
            if x - next_x > -1 and x - next_x <= 0:
                break
            x = next_x

        return int(x)


if __name__ == "__main__":
    print(Solution().mySqrt(13))
    print(Solution().mySqrt(16))