import sys
sys.setrecursionlimit(700000)
N = int(input())
S = input()

cur = 0
l = 0
s1 = "CPCTF"
s2 = "CPCTCPC"
cnt = 0

mem = {}
def f(s):
    if len(s)<5:
        return 0
    a = [f(s[1:])]
    if s.startswith(s1):
        if len(s)-len(s1) not in mem:
            mem[len(s)-len(s1)] = f(s[len(s1):])
        a.append(mem[len(s)-len(s1)]+1)
    if s.startswith(s2):
        if len(s)-len(s2) not in mem:
            mem[len(s)-len(s2)] = f(s[len(s2):])
        a.append(mem[len(s)-len(s2)]+1)
    return max(a)
print(f(S)) 
"🐬?"