class Main {
  public static void main(String[] args){
    String str = "AAAA"; // Expected output: 3
    countChars(str);
    System.out.println(count);
  }
 
  private static int count = 0;
  private static void countChars(String str){
    int length = str.length();
    for(int i = 1; i < length; i++){
      if(str.charAt(i-1) == str.charAt(i)){
        count++;
        String substr = str.substring(i, length);
        countChars(substr);
        break;
      }
    }
  }
}

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