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

count = 0

# Check for "CPCTF" substrings
for i in range(len(s) - 4):
    if s[i:i+5] == "CPCTF":
        count += 1

# Check for "CPCTCPC" substrings
for i in range(len(s) - 6):
    if s[i:i+7] == "CPCTCPC":
        count += 1

print(count)