N=int(input())
S=input()
T=""
i=0
tmp=""
while i<N:
    tmp+=S[i]
    if len(T)>=4 and T[-4:]=="CPCT":
        for _ in range(2):
            i+=1
            if i==N:break
            tmp+=S[i]
        if tmp=="CPC":T+="F"
        else:T+=tmp
        tmp=""
    else:
        T+=tmp
        tmp=""
    i+=1
print(T.count("CPCTF"))