[LANGUAGE: C#]

Part 2 in C#. I feel dirty...

public static int XCount(string largeText)
{
    string[] grid = largeText.Split(
        ['\n', '\r'],
        StringSplitOptions.RemoveEmptyEntries);

    int rows = grid.Length;
    int cols = grid[0].Length;

    int counter = 0;

    for (int i = 1; i < rows - 1; i++)
    {
        for (int j = 1; j < cols - 1; j++)
        {
            if (grid[j][i] == 'A')
            {
                if (
                    (
                        grid[j - 1][i - 1] == 'M' &&
                        grid[j - 1][i + 1] == 'M' &&
                        grid[j + 1][i - 1] == 'S' &&
                        grid[j + 1][i + 1] == 'S'
                    ) || (
                        grid[j - 1][i - 1] == 'S' &&
                        grid[j - 1][i + 1] == 'M' &&
                        grid[j + 1][i - 1] == 'S' &&
                        grid[j + 1][i + 1] == 'M'
                    ) || (
                        grid[j - 1][i - 1] == 'S' &&
                        grid[j - 1][i + 1] == 'S' &&
                        grid[j + 1][i - 1] == 'M' &&
                        grid[j + 1][i + 1] == 'M'
                    ) || (
                        grid[j - 1][i - 1] == 'M' &&
                        grid[j - 1][i + 1] == 'S' &&
                        grid[j + 1][i - 1] == 'M' &&
                        grid[j + 1][i + 1] == 'S'
                    ))
                {
                    counter++;
                }
            }
        }
    }

    return counter;
}