4014 - Good Matrix Elements

4014.Good Matrix Elements

Time Limit: 1s Memory Limit: 256MB

The Smart Beaver from ABBYY got hooked on square matrices. Now he is busy studying an n \times 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 $4014_1.png$ rows above it and the same number of rows below it. Elements of the "middle" column - the column that has exactly $4014_1.png$ columns to the left of it and the same number of columns to the right of it. $4014_2.png$ The figure shows a 5 \times 5 matrix. The good elements are marked with green. Help the Smart Beaver count the sum of good elements of the given matrix.

Input Format(From the terminal/stdin)

Input The first line of input data contains a single odd integer n. Each of the next n lines contains n integers aij (0 \le aij \le 100) separated by single spaces - the elements of the given matrix.The input limitations for getting 30 points are: 1 \le n \le 5 The input limitations for getting 100 points are: 1 \le n \le 101

Output Format(To the terminal/stdout)

Output Print a single integer - the sum of good matrix elements.

Sample Input 1

Copy

3
1 2 3
4 5 6
7 8 9
 \n
 · · \n
 · · \n
 · · \n

Sample Output 1

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45
  \n

Sample Input 2

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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
 \n
 · · · · \n
 · · · · \n
 · · · · \n
 · · · · \n
 · · · · \n

Sample Output 2

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17
  \n

Hints

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

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