public static void main ( String [ ] args ) throws IOException {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  HashMap < Character , Integer > m = new HashMap < Character , Integer > ( ) ;
  int n = Integer . parseInt ( br . readLine ( ) ) ;
  String s = br . readLine ( ) . trim ( ) ;
  int l = s . length ( ) ;
  int count = 0 ;
  ;
}

public static void main ( String [ ] args ) throws IOException { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; HashMap < Character , Integer > m = new HashMap < Character , Integer > ( ) ; int n = Integer . parseInt ( br . readLine ( ) ) ; String s = br . readLine ( ) . trim ( ) ; int l = s . length ( ) ; int count = 0 ; ; }
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