Big J needs to walk around the school, visiting multiple locations such as the main oval, the science hub, the music school, the library, etc. He is a very busy man and therefore needs to accurately plan out his schedule.

You, as his number one student, will need to help him calculate how long it will take for him to walk around the school.

You will be given a list of times, showing how long it takes for Big J to travel between 2 locations.

Input

The input will be of 2 lines.

The first line will contain an integer N (1 ≤ N ≤ 10⁵), the number of stops he is going to stop at.

The second line will contain an array A of N - 1 integers (1 ≤ A_i ≤ 60), each showing the minutes required to move between 2 locations.

Output

Output a single integer, the total amount of time required for him to get from the first location to the last.

Example

Input:
5
3 8 1 3

Output:
15