public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  String s = sc . next ( ) ;
  int len = s . length ( ) ;
  StringBuilder sb = new StringBuilder ( ) ;
  int p = 0 ;
  int m = len ;
  if ( ( s . length ( ) & 1 ) == 0 ) {
    while ( len > 0 ) {
      sb . append ( s . charAt ( m - p - 1 ) ) ;
      sb . append ( s . charAt ( p ) ) ;
      p ++ ;
      len -= 2 ;
    }
    sb . reverse ( ) ;
    System . out . println ( sb ) ;
  }
  else {
    while ( len > 0 ) {
      sb . append ( s . charAt ( p ) ) ;
      sb . append ( s . charAt ( m - p - 1 ) ) ;
      p ++ ;
      len -= 2 ;
    }
    sb . reverse ( ) ;
    sb . deleteCharAt ( 0 ) ;
    System . out . println ( sb ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; String s = sc . next ( ) ; int len = s . length ( ) ; StringBuilder sb = new StringBuilder ( ) ; int p = 0 ; int m = len ; if ( ( s . length ( ) & 1 ) == 0 ) { while ( len > 0 ) { sb . append ( s . charAt ( m - p - 1 ) ) ; sb . append ( s . charAt ( p ) ) ; p ++ ; len -= 2 ; } sb . reverse ( ) ; System . out . println ( sb ) ; } else { while ( len > 0 ) { sb . append ( s . charAt ( p ) ) ; sb . append ( s . charAt ( m - p - 1 ) ) ; p ++ ; len -= 2 ; } sb . reverse ( ) ; sb . deleteCharAt ( 0 ) ; System . out . println ( sb ) ; } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (identifier))) (if_statement condition: (parenthesized_expression (binary_expression left: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal))) right: (decimal_integer_literal))) consequence: (block (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))) alternative: (block (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal))))))) (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal)))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))))