Number of tangents
A tangent to a circle is a line that touches the circle at exactly one point. A line can be tangent to two circles at the same time, in which case it is called a common tangent.
Write a program to determine the number of distinct common tangents for two given circles. If the number of common tangents exceeds 6, output the number 7, following the ancient tradition where 7 signifies "many."
Input
The program reads two lines from the input, each containing three integers (each not exceeding one million in absolute value) separated by spaces: X_1, Y_1, R_1, X_2, Y_2, R_2. These represent the coordinates of the centers and the radii of the 1st and 2nd circles, respectively.
Output
The program should output the number of common tangents, considering the ancient tradition mentioned above.