353D - Queue - CodeForces Solution

seq = input()
seq = seq[seq.find('M'):]

n_girls = seq.count('F')
last_girl = seq.rfind('F')

i = last_girl - 1
delay = 0
delta = 1
chk = 'M'
max_delay = 0
while i > 0:
    if seq[i] == chk:
        delta *= -1
        chk = 'F' if chk == 'M' else 'M'
        continue
    i -= 1
    delay += delta
        if delay > max_delay:
        max_delay = delay

print(last_girl - n_girls + 1 + max_delay)