Find the sum of both the primary and secondary diagonal elements of a square matrix.

Difficulty: Medium

Phase: 6 · Mixed Logical Challenges

XP Reward: 20 XP

Topics: Mixed Logical Challenges, Medium

Supported Languages: Python, JavaScript, C, C++, Java

Problem Description

Given N followed by N x N matrix, find sum of both primary and secondary diagonals (if N is odd, center element counted once). Input Format: Read input from standard input (stdin). Output Format: Print the result to standard output (stdout).

Constraints

-10^9 <= N <= 10^9

Examples

Example 1

Input: 3 1 2 3 4 5 6 7 8 9

Output: 25

Explanation: Sample execution for input 3 1 2 3 4 5 6 7 8 9