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n = int(input())
results = input()

cnt = 0
group = n / 10
correct_tests = 0
answer = 0
for i in range(n):
    cnt += 1
    if results[i] == 'T':
        correct_tests += 1
    if cnt == group:
        if correct_tests == group:
            answer += 1
        cnt = 0
        correct_tests = 0

print(answer)