public static void main ( String args [ ] ) {
  Scanner in = new Scanner ( System . in ) ;
  int n = in . nextInt ( ) ;
  String s = in . next ( ) ;
  int cx = 0 , cX = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( s . charAt ( i ) == 'x' ) cx ++ ;
    else cX ++ ;
  }
  System . out . println ( Math . abs ( n / 2 - cx ) ) ;
  String str = "" ;
  int x = cx - n / 2 ;
  for ( int i = 0 ;
  i < n && x > 0 ;
  i ++ ) {
    if ( s . charAt ( i ) == 'x' ) {
      s = s . substring ( 0 , i ) + ( char ) ( s . charAt ( i ) - 32 ) + s . substring ( i + 1 , n ) ;
      x -- ;
    }
  }
  x = cX - n / 2 ;
  for ( int i = 0 ;
  i < n && x > 0 ;
  i ++ ) {
    if ( s . charAt ( i ) == 'X' ) {
      s = s . substring ( 0 , i ) + ( char ) ( s . charAt ( i ) + 32 ) + s . substring ( i + 1 , n ) ;
      x -- ;
    }
  }
  System . out . println ( s ) ;
}

public static void main ( String args [ ] ) { Scanner in = new Scanner ( System . in ) ; int n = in . nextInt ( ) ; String s = in . next ( ) ; int cx = 0 , cX = 0 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) == ' x ' ) cx ++ ; else cX ++ ; } System . out . println ( Math . abs ( n / 2 - cx ) ) ; String str = " " ; int x = cx - n / 2 ; for ( int i = 0 ; i < n && x > 0 ; i ++ ) { if ( s . charAt ( i ) == ' x ' ) { s = s . substring ( 0 , i ) + ( char ) ( s . charAt ( i ) - 32 ) + s . substring ( i + 1 , n ) ; x -- ; } } x = cX - n / 2 ; for ( int i = 0 ; i < n && x > 0 ; i ++ ) { if ( s . charAt ( i ) == ' X ' ) { s = s . substring ( 0 , i ) + ( char ) ( s . charAt ( i ) + 32 ) + s . substring ( i + 1 , n ) ; x -- ; } } System . out . println ( s ) ; }
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