file = open('13.txt')
text = file.read()
count = 0
for i in range(len(text) - 7):
    if text[i] == "A" and ( text[i + 6] == "F" or text[i + 7] == "F" or text[i + 8] == "F" or text[i + 9] == "F" ):
        count += 1
print(count)