#!/usr/bin/python3.9

import functools

def calc_test(test):
    return functools.reduce(lambda x,y:x*y, map(lambda x: 1 if x == 'T' else 0, test))

n = int(input())
s = input()
testlen = n//10

l = [ s[i:i+testlen] for i in range(0, n, testlen) ]
print(functools.reduce(lambda x,y:x+y, map(calc_test, l)))

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#!/usr/bin/python3.9

import functools

def calc_test(test):
    return functools.reduce(lambda x,y:x*y, map(lambda x: 1 if x == 'T' else 0, test))

n = int(input())
s = input()
testlen = n//10

l = [ s[i:i+testlen] for i in range(0, n, testlen) ]
print(functools.reduce(lambda x,y:x+y, map(calc_test, l)))