import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

import re
n = ni()
s = input()
s = (s[::-1].replace("CPC", "A"))[::-1]
S = re.split("C|P", s)
#print(s)
ans = 0
for s in S:
    s = list(s)
    for i in range(len(s)):
        #print(s[i: i+3], ans)
        if s[i: i+3] == ["A", "T", "A"] or s[i:i+3] == ["A", "T", "F"]:
            ans += 1
            s[i+2] = "F"
print(ans)