using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        WriteLine(CPC(n, s));
    }
    static int CPC(int n, string s)
    {
        var pos = 0;
        var ans = 0;
        while(pos < n)
        {
            if (pos + 5 <= n && s[pos..(pos+5)] == "CPCTF")
            {
                ++ans;
                pos += 5;
            }
            else if (pos + 7 <= n && s[pos..(pos+7)] == "CPCTCPC")
            {
                ++ans;
                pos += 7;
            }
            else ++pos;
        }
        return ans;
    }
}