using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var N = int.Parse(Console.ReadLine());
        var S = Console.ReadLine() + "C";
        
        var count = 0;

        for (int i = 0; i < N - 1; i++)
        {
            if (S.Substring(i, 2) != "BB" && S.Substring(i, 3) != "BAB") count++;
        }

        if (S.Contains("BB")) count++;
        Console.WriteLine(count);
    }
}