verbose = False

def x_mas_at(M, i: int, j: int) -> bool:
	# NOTE: Checking i and j are not on the boundary is wise.

	top_left  = \
		M[i - 1][j - 1] == "M" and M[i + 1][j + 1] == "S" or \
		M[i - 1][j - 1] == "S" and M[i + 1][j + 1] == "M"
	top_right = \
		M[i + 1][j - 1] == "M" and M[i - 1][j + 1] == "S" or \
		M[i + 1][j - 1] == "S" and M[i - 1][j + 1] == "M"

	return top_left and top_right

if __name__ == "__main__":
	result = 0
	
	with open("input", "r") as fp:
		# Skip last line as it is empty.
		full_string = fp.read().split("\n")[:-1]

		x_mas_count = 0
		
		for i in range(1, len(full_string) - 1):
			for j in range(1, len(full_string[0]) - 1):
				if full_string[i][j] == "A":
					if x_mas_at(full_string, i, j):
						x_mas_count += 1

	print(f"The sum of all horizontal X-MASs equals {x_mas_count}.")