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# with open("test.in") as file:
#     file = file.readlines()

# n = int(file[0].strip())
# wyn = file[1].strip()
n = int(input())
wyn = input()
ileTestow = n // 10
s = 0
i = 0
wzor = "T"*ileTestow
while i < n:
    if wyn[i:i+ileTestow] == wzor:
        s+=1
    i += ileTestow
print(s)