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