Academic Distance

Interview

Time limit2sMemory limit512 MB

Summary

Given N points in order, compute the total Manhattan distance along the path from the first point to the last.

Level: Easy1 of 10
Topics: Implementation, Math, Array
Solved: No attempts yet

Problem

Starting from the second semester, Mr. Eto will take classes at Kyoto University. He is not accustomed to the structure of the university because in the first semester he had only online lectures.

There are $N$ classes today. The schedule contains the coordinates of $N$ classrooms in the order in which they have to be visited. The coordinates of the $i$ -th classroom are $(x_i, y_i)$ . Assuming Mr. Eto starts the day in the first classroom and ends in the $N$ -th classroom, calculate the total distance he has to travel.

On the Kyoto University campus, the distance traveled from the coordinates $(a, b)$ to the coordinates $(c, d)$ is $|a-c| + |b-d|$ .

Input

The first line of the input contains one integer $N$ ( $1 \le N \le 100$ ), the number of classrooms in today's schedule. Then $N$ lines follow, the $i$ -th of them containing the integer coordinates $x_i$ and $y_i$ of the $i$ -th classroom in the schedule ( $-100 \le x_i, y_i \le 100$ ).

Output

Print one integer: the total distance traveled by Mr. Eto by the end of the day.

Examples3

Example 1
Input
```
3
1 2
2 3
4 6
```
Expected output
```
7
```
Example 2
Input
```
1
0 0
```
Expected output
```
0
```
Example 3
Input
```
4
-2 3
1 4
5 2
4 -2
```
Expected output
```
15
```