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

original_positions = set()

# Find all original CPCTF substrings
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':
        original_positions.add(i)
original = len(original_positions)

cpc_positions = []
# Find all CPC substrings
for i in range(n - 2):
    if s[i] == 'C' and s[i+1] == 'P' and s[i+2] == 'C':
        cpc_positions.append(i)

additional = 0

# Check each CPC for potential new CPCTF
for i in cpc_positions:
    if i - 4 >= 0:
        if s[i-4] == 'C' and s[i-3] == 'P' and s[i-2] == 'C' and s[i-1] == 'T':
            # Check if this CPC is part of any original CPCTF
            if i not in original_positions:
                additional += 1

print(original + additional)