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

i, current, cnt = 0, 0, 0
while i <= N:
    s = S[current:i]
    if (s == 'CPCTF'):
        cnt += 1
        i += 1
        current += 5
    elif (s == 'CPCTCPC'):
        cnt += 1
        i += 1
        current += 6
    else:
        i += 1

print(cnt)