eolymp
bolt
Try our new interface for solving problems
Problems

Diagonals

Diagonals

Time limit 1 second
Memory limit 128 MiB

In the square table n \cdot n find the sum of integers at the main and the secondary diagonals.

Input data

The first line contains the size n~(1 \le n \le 500) of the matrix. The next lines describe a matrix n \cdot n. The elements of the matrix are not greater than 10^5 by absolute value.

Output data

Print the sum of the integers at the main and the secondary diagonals.

Examples

Input example #1
4
1 2 3 4
5 6 7 8
3 2 5 4
8 7 9 3
Output example #1
15 21