public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int t = sc . nextInt ( ) ;
  for ( int i = 0 ;
  i < t ;
  i ++ ) {
    int n = sc . nextInt ( ) ;
    String s = "" ;
    for ( int j = 0 ;
    j < n ;
    j ++ ) {
      s += sc . next ( ) ;
    }
    boolean isTrue = true ;
    while ( s . length ( ) > 0 ) {
      String s1 = s . substring ( 0 , 1 ) ;
      int count = 0 ;
      for ( int j = 0 ;
      j < s . length ( ) ;
      j ++ ) {
        if ( s1 . equals ( s . substring ( j , j + 1 ) ) ) count ++ ;
      }
      s = s . replace ( s1 , "" ) ;
      if ( count >= n ) {
        if ( n % 2 == 0 ) {
          if ( count % 2 != 0 ) isTrue = false ;
        }
        else {
          if ( count % n != 0 ) isTrue = false ;
        }
      }
      else {
        isTrue = false ;
        break ;
      }
    }
    if ( isTrue ) {
      System . out . println ( "YES" ) ;
    }
    else {
      System . out . println ( "NO" ) ;
    }
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int t = sc . nextInt ( ) ; for ( int i = 0 ; i < t ; i ++ ) { int n = sc . nextInt ( ) ; String s = " " ; for ( int j = 0 ; j < n ; j ++ ) { s += sc . next ( ) ; } boolean isTrue = true ; while ( s . length ( ) > 0 ) { String s1 = s . substring ( 0 , 1 ) ; int count = 0 ; for ( int j = 0 ; j < s . length ( ) ; j ++ ) { if ( s1 . equals ( s . substring ( j , j + 1 ) ) ) count ++ ; } s = s . replace ( s1 , " " ) ; if ( count >= n ) { if ( n % 2 == 0 ) { if ( count % 2 != 0 ) isTrue = false ; } else { if ( count % n != 0 ) isTrue = false ; } } else { isTrue = false ; break ; } } if ( isTrue ) { System . out . println ( " YES " ) ; } else { System . out . println ( " NO " ) ; } } }
(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: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_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 (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (boolean_type) declarator: (variable_declarator name: (identifier) value: (true))) (while_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (decimal_integer_literal))))) (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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (identifier) right: (decimal_integer_literal))))))) consequence: (expression_statement (update_expression (identifier)))))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (string_literal))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal))) consequence: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal))) consequence: (expression_statement (assignment_expression left: (identifier) right: (false))))) alternative: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal))) consequence: (expression_statement (assignment_expression left: (identifier) right: (false))))))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (false))) (break_statement))))) (if_statement condition: (parenthesized_expression (identifier)) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))))))))