N = int(input())
S = input()

i=3
cnt = 0

while i < N-1:
    c = S[i]
    if c != "T":
        i += 1
        continue
    
    if S[i-3:i] == "CPC":
        if S[i+1] == "F":
            cnt += 1
            i += 5
        elif i+3 < N and S[i+1:i+4] == "CPC":
            cnt += 1
            i += 7
        else:
            continue
    else:
        i += 4
        
print(cnt)