I. Red and yellow
time limit per test
2 seconds
memory limit per test
64 megabytes
input
standard input
output
standard output

You can have one red circle with radius in the range [A;B] and unlimited number of yellow circles with radius R. Task is to put all circles in a way that each yellow circle touches 2 other yellow circles and 1 red circle. A circle cannot be inside another circle. Calculate how many different real sizes (X) of the red circle radius can satisfy this condition.

Input

A single line contains 3 integers A, B and R. (1 ≤ A, B, R ≤ 107, A ≤ B)

Output

Print a single integer X.

Examples
Input
2 2 2
Output
1
Input
1 2 2
Output
2