#include <iostream>
using namespace std;
 
int n, a[100][100];
 
int tinhtong(int a[100][100], int n, int x, int y)
{
	int sum = 0;
 
	for(int i = -1 ; i <= 1 ; i ++)
		for (int j = -1; j <= 1; j++)
		{
			if (y + i >= 0 && x + j < n && y + i < n && x + j >= 0)
				sum += a[y + i][x + j];
		}
	return sum - a[y][x];
}
 
int main()
{
	cin >> n;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < n; j++)
			cin >> a[i][j];
	cout << tinhtong(a, n, 2, 1);
	return 0;
}
/*
3
1 2 3 
4 5 6
7 8 9
*/

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MwoxIDIgMyAKNCA1IDYKNyA4IDk=

3
1 2 3 
4 5 6
7 8 9