Contest: Task: Related: TaskB

Score : $100$ points

We have a number line. Takahashi painted some parts of this line, as follows:

- First, he painted the part from $X=L_1$ to $X=R_1$ red.
- Next, he painted the part from $X=L_2$ to $X=R_2$ blue.

Find the length of the part of the line painted both red and blue.

- $0\leq L_1<R_1\leq 100$
- $0\leq L_2<R_2\leq 100$
- All values in input are integers.

Input is given from Standard Input in the following format:

$L_1$ $R_1$ $L_2$ $R_2$

Print the length of the part of the line painted both red and blue, as an integer.

0 3 1 5

2

The part from $X=0$ to $X=3$ is painted red, and the part from $X=1$ to $X=5$ is painted blue.

Thus, the part from $X=1$ to $X=3$ is painted both red and blue, and its length is $2$.

0 1 4 5

0

No part is painted both red and blue.

0 3 3 7

0

If the part painted red and the part painted blue are adjacent to each other, the length of the part painted both red and blue is $0$.