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Good Matrix Elements

2000ms 262144K

Description:

The Smart Beaver from ABBYY got hooked on square matrices. Now he is busy studying an n × n size matrix, where n is odd. The Smart Beaver considers the following matrix elements good:

  • Elements of the main diagonal.
  • Elements of the secondary diagonal.
  • Elements of the "middle" row — the row which has exactly rows above it and the same number of rows below it.
  • Elements of the "middle" column — the column that has exactly columns to the left of it and the same number of columns to the right of it.
The figure shows a 5 × 5 matrix. The good elements are marked with green.

Help the Smart Beaver count the sum of good elements of the given matrix.

Input:

The first line of input data contains a single odd integer n. Each of the next n lines contains n integers aij (0 ≤ aij ≤ 100) separated by single spaces — the elements of the given matrix.

The input limitations for getting 30 points are:

  • 1 ≤ n ≤ 5

The input limitations for getting 100 points are:

  • 1 ≤ n ≤ 101

Output:

Print a single integer — the sum of good matrix elements.

Sample Input:

3
1 2 3
4 5 6
7 8 9

Sample Output:

45

Sample Input:

5
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1

Sample Output:

17

Note:

In the first sample all matrix elements will be good. Good elements in the second sample are shown on the figure.

Informação

Codeforces

Provedor Codeforces

Código CF177A1

Tags

implementation

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Datas 09/05/2023 08:36:09

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