N=int(input())
S=input()
T=list(S)
for i in range(N-4):
    if S[i:i+4]=="CPCT" and i+7<=N and S[i+4:i+7]=="CPC":
        T[i+4]="F";T[i+5]="F";T[i+6]="F"
T="".join(T)
print(T.count("CPCTF"))