using System;
public class Program
{
public static void Main()
Console.WriteLine(test("bbaaccaag"));
Console.WriteLine(test("jjkiaaasew"));
Console.WriteLine(test("JSaaakoiaa"));
Console.ReadLine();
}
public static int test(string s)
int ctr_aa = 0;
for (int i = 0; i < s.Length - 1; i++)
if (s.Substring(i, 2) == "aa")
ctr_aa++;
return ctr_aa;