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n = int(input())
S = str(input())
k = n//10
odp = 0
for p in range(0, n-k+1, k):
	ok=True
	for i in range(p+1, p+k):
		if S[i-1] != S[i]:
			ok=False
	if ok and S[p] == 'T':
		odp += 1
print(odp)