public static void main ( String args [ ] ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int x [ ] = new int [ n ] ;
  int y [ ] = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    x [ i ] = sc . nextInt ( ) ;
    y [ i ] = sc . nextInt ( ) ;
  }
  double line = 0.0 ;
  for ( int i = 0 ;
  i < n - 1 ;
  i ++ ) {
    for ( int j = i + 1 ;
    j < n ;
    j ++ ) {
      double line2 = ( double ) Math . pow ( x [ i ] - x [ j ] , 2 ) + ( double ) Math . pow ( y [ i ] - y [ j ] , 2 ) ;
      if ( line < line2 ) {
        line = line2 ;
      }
    }
  }
  double answer = Math . sqrt ( line ) ;
  System . out . println ( answer ) ;
}

public static void main ( String args [ ] ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int x [ ] = new int [ n ] ; int y [ ] = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { x [ i ] = sc . nextInt ( ) ; y [ i ] = sc . nextInt ( ) ; } double line = 0.0 ; for ( int i = 0 ; i < n - 1 ; i ++ ) { for ( int j = i + 1 ; j < n ; j ++ ) { double line2 = ( double ) Math . pow ( x [ i ] - x [ j ] , 2 ) + ( double ) Math . pow ( y [ i ] - y [ j ] , 2 ) ; if ( line < line2 ) { line = line2 ; } } } double answer = Math . sqrt ( line ) ; System . out . println ( answer ) ; }
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