n = int(input())
s = input().strip()

count_cpctf = 0
for i in range(n - 4):
    if s[i] == 'C' and s[i+1] == 'P' and s[i+2] == 'C' and s[i+3] == 'T' and s[i+4] == 'F':
        count_cpctf += 1

count_cpctcpc = 0
for i in range(n - 6):
    if (s[i] == 'C' and s[i+1] == 'P' and s[i+2] == 'C' and
        s[i+3] == 'T' and
        s[i+4] == 'C' and s[i+5] == 'P' and s[i+6] == 'C'):
        count_cpctcpc += 1

print(count_cpctf + count_cpctcpc)