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if __name__ == "__main__":
    n = int(input())
    results = input()
    tests_per_group = n // 10
    all_passed = "T" * tests_per_group

    points = [
        1
        for i in range(0, len(results), tests_per_group)
        if results[i : i + tests_per_group] == all_passed
    ]
    print(sum(points))