Contest Duration: - (local time) (100 minutes) Back to Home
A - Intersection /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 問題文

• X=L_1 から X=R_1 までをすべて赤色で塗る。
• X=L_2 から X=R_2 までをすべて青色で塗る。

### 制約

• 0\leq L_1<R_1\leq 100
• 0\leq L_2<R_2\leq 100
• 入力はすべて整数

### 入力

L_1 R_1 L_2 R_2


### 入力例 1

0 3 1 5


### 出力例 1

2


X=0 から X=3 までが赤く、 X=1 から X=5 までが青く塗られています。

よって、両方の色で塗られている部分は X=1 から X=3 までであり、その長さは 2 となります。

### 入力例 2

0 1 4 5


### 出力例 2

0


### 入力例 3

0 3 3 7


### 出力例 3

0


Score : 100 points

### Problem Statement

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.

### Constraints

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

### Input

Input is given from Standard Input in the following format:

L_1 R_1 L_2 R_2


### Output

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

### Sample Input 1

0 3 1 5


### Sample Output 1

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.

### Sample Input 2

0 1 4 5


### Sample Output 2

0


No part is painted both red and blue.

### Sample Input 3

0 3 3 7


### Sample Output 3

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.