public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int t = sc . nextInt ( ) ;
  for ( int l = 0 ;
  l < t ;
  l ++ ) {
    int n = sc . nextInt ( ) ;
    HashMap < Character , Integer > h = new HashMap < > ( ) ;
    int count = 0 , e = 0 ;
    for ( int k = 0 ;
    k < n ;
    k ++ ) {
      String s = sc . next ( ) ;
      for ( int i = 0 ;
      i < s . length ( ) ;
      i ++ ) {
        char ch = s . charAt ( i ) ;
        if ( ! h . containsKey ( ch ) ) h . put ( ch , 1 ) ;
        else {
          int v = h . get ( ch ) + 1 ;
          h . put ( ch , v ) ;
        }
      }
    }
    for ( char ch : h . keySet ( ) ) {
      if ( h . get ( ch ) % n == 0 ) count ++ ;
      else {
        e ++ ;
        System . out . println ( "NO" ) ;
        break ;
      }
    }
    if ( e == 0 ) System . out . println ( "YES" ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int t = sc . nextInt ( ) ; for ( int l = 0 ; l < t ; l ++ ) { int n = sc . nextInt ( ) ; HashMap < Character , Integer > h = new HashMap < > ( ) ; int count = 0 , e = 0 ; for ( int k = 0 ; k < n ; k ++ ) { String s = sc . next ( ) ; for ( int i = 0 ; i < s . length ( ) ; i ++ ) { char ch = s . charAt ( i ) ; if ( ! h . containsKey ( ch ) ) h . put ( ch , 1 ) ; else { int v = h . get ( ch ) + 1 ; h . put ( ch , v ) ; } } } for ( char ch : h . keySet ( ) ) { if ( h . get ( ch ) % n == 0 ) count ++ ; else { e ++ ; System . out . println ( " NO " ) ; break ; } } if ( e == 0 ) System . out . println ( " YES " ) ; } }
(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: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (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: (generic_type (type_identifier) (type_arguments (type_identifier) (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) 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: (identifier)) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) (if_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (decimal_integer_literal)))) alternative: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (decimal_integer_literal)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier)))))))))) (enhanced_for_statement type: (integral_type) name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (identifier)) right: (decimal_integer_literal))) consequence: (expression_statement (update_expression (identifier))) alternative: (block (expression_statement (update_expression (identifier))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) (break_statement))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))))))))