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n = int(input())
lista = input()
pom = 0
pom2 = 0
for i in range(10):
    for j in range(n // 10):
        if lista[(i*(n//10))+j] == 'T':
            pom += 1
        else:
            break
    if pom == n/10:
        pom2 += 1
    pom = 0
print(pom2)