Consider a square chess board with *n* rows and *n* columns,
where every square contains between 0 and 9 coins.
Write a program such that, given a chess board,
computes the total number of coins on its two diagonals.

**Input**

Input begins with the size *n* of the board.
Follow *n* lines, each one with *n* characters
between ‘`0`’ and ‘`9`’.

**Output**

Print the total number of coins on the two diagonals of the board.

Public test cases

**Input**

4 2389 3402 3956 2018

**Output**

39

**Input**

3 975 123 450

**Output**

20

Information

- Author
- Salvador Roura
- Language
- English
- Translator
- Salvador Roura
- Original language
- Catalan
- Other languages
- Catalan
- Official solutions
- C++ Java Python
- User solutions
- C C++ Java Python