def main():
    N = int(input())
    S = input()
    idx = -1
    ctr = 0
    while idx < N:
        search_idx = S.find("CPCT", idx + 1)
        if search_idx == -1:
            break
        if search_idx + 4 >= N:
            break
        if S[search_idx + 4] == "F":
            ctr += 1
            idx = search_idx
            continue
        if S[search_idx + 4:search_idx + 7] == "CPC":
            ctr += 1
            idx = search_idx + 4
    print(ctr)


if __name__ == "__main__":
    main()