def main():
    N = int(input())
    S = list(input())

    for i in range(N):
        if i + 7 <= N and S[i:i+7] == ['C', 'P', 'C', 'T', 'C', 'P', 'C']:
            S[i + 4: i + 7] = ['F', ' ', ' ']

    ans = 0

    for i in range(N):
        if i + 5 <= N and S[i: i + 5] == ['C', 'P', 'C', 'T', 'F']:
            ans += 1

    print(ans)
    return 0


main()