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