public static void main ( String [ ] args ) throws IOException {
  init ( System . in ) ;
  int n = nextInt ( ) ;
  int A [ ] = new int [ 2 * n ] ;
  for ( int i = 0 ;
  i < 2 * n ;
  i ++ ) {
    A [ i ] = nextInt ( ) ;
  }
  Arrays . sort ( A ) ;
  int sum = 0 ;
  for ( int i = 0 ;
  i < 2 * n ;
  i += 2 ) {
    if ( A [ i ] < A [ i + 1 ] ) {
      sum += A [ i ] ;
    }
    else {
      sum += A [ i + 1 ] ;
    }
  }
  System . out . println ( sum ) ;
}

public static void main ( String [ ] args ) throws IOException { init ( System . in ) ; int n = nextInt ( ) ; int A [ ] = new int [ 2 * n ] ; for ( int i = 0 ; i < 2 * n ; i ++ ) { A [ i ] = nextInt ( ) ; } Arrays . sort ( A ) ; int sum = 0 ; for ( int i = 0 ; i < 2 * n ; i += 2 ) { if ( A [ i ] < A [ i + 1 ] ) { sum += A [ i ] ; } else { sum += A [ i + 1 ] ; } } System . out . println ( sum ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_identifier)) body: (block (expression_statement (method_invocation name: (identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (binary_expression left: (decimal_integer_literal) right: (identifier)))))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (binary_expression left: (decimal_integer_literal) right: (identifier))) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation name: (identifier) arguments: (argument_list)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (binary_expression left: (decimal_integer_literal) right: (identifier))) update: (assignment_expression left: (identifier) right: (decimal_integer_literal)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (array_access array: (identifier) index: (identifier))))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))