public static void main ( String [ ] args ) throws IOException {
  FastReader sc = new FastReader ( ) ;
  PrintWriter out = new PrintWriter ( System . out ) ;
  int n = sc . nextInt ( ) ;
  String str = sc . next ( ) ;
  char [ ] dir = str . toCharArray ( ) ;
  int [ ] pos = sc . nextIntArray ( n ) ;
  if ( str . replaceAll ( "RL" , "" ) . length ( ) == n ) out . println ( - 1 ) ;
  else {
    int min = Integer . MAX_VALUE ;
    for ( int i = 0 ;
    i < n - 1 ;
    i ++ ) {
      if ( dir [ i ] == 'R' && dir [ i + 1 ] == 'L' ) min = Math . min ( min , pos [ i + 1 ] - pos [ i ] ) ;
    }
    out . println ( min / 2 ) ;
  }
  out . close ( ) ;
}

public static void main ( String [ ] args ) throws IOException { FastReader sc = new FastReader ( ) ; PrintWriter out = new PrintWriter ( System . out ) ; int n = sc . nextInt ( ) ; String str = sc . next ( ) ; char [ ] dir = str . toCharArray ( ) ; int [ ] pos = sc . nextIntArray ( n ) ; if ( str . replaceAll ( " RL " , " " ) . length ( ) == n ) out . println ( - 1 ) ; else { int min = Integer . MAX_VALUE ; for ( int i = 0 ; i < n - 1 ; i ++ ) { if ( dir [ i ] == ' R ' && dir [ i + 1 ] == ' L ' ) min = Math . min ( min , pos [ i + 1 ] - pos [ i ] ) ; } out . println ( min / 2 ) ; } out . close ( ) ; }
(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 (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: (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: (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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal) (string_literal))) name: (identifier) arguments: (argument_list)) right: (identifier))) consequence: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal))))) alternative: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (field_access object: (identifier) field: (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: (identifier) right: (decimal_integer_literal))) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (character_literal)) right: (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (character_literal)))) consequence: (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (array_access array: (identifier) index: (identifier)))))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))