C++ :

#include <iostream>

using namespace std;

int a=0;
void fn(char n)
{
	if(n=='a'||n=='A')
		a++;
}
int main()
{
	char c;
	while(cin>>c&&c!='#')
	{
		fn(c);
	}
	cout<<a<<endl;
	return 0;
}

Pascal :

var
 n:char;
 k,i:integer;
 begin
 while n<>'#' do
  begin
  read(n);
  if (n='a') or (n='A') then k:=k+1;
  end;
  write(k);
  end.