public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) , k = sc . nextInt ( ) ;
  boolean [ ] rp = new boolean [ n ] ;
  String [ ] arr = new String [ n ] ;
  for ( int i = 0 ;
  i < n - k + 1 ;
  ++ i ) {
    rp [ i ] = sc . next ( ) . equals ( "NO" ) ;
  }
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    if ( arr [ i ] == null ) arr [ i ] = ( i < 25 ? "A" : "B" ) + ( char ) ( 'a' + i % 25 ) ;
    if ( rp [ i ] ) {
      arr [ i + k - 1 ] = arr [ i ] ;
    }
  }
  for ( String s : arr ) System . out . print ( s + " " ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) , k = sc . nextInt ( ) ; boolean [ ] rp = new boolean [ n ] ; String [ ] arr = new String [ n ] ; for ( int i = 0 ; i < n - k + 1 ; ++ i ) { rp [ i ] = sc . next ( ) . equals ( " NO " ) ; } for ( int i = 0 ; i < n ; ++ i ) { if ( arr [ i ] == null ) arr [ i ] = ( i < 25 ? " A " : " B " ) + ( char ) ( ' a ' + i % 25 ) ; if ( rp [ i ] ) { arr [ i + k - 1 ] = arr [ i ] ; } } for ( String s : arr ) System . out . print ( s + " ▁ " ) ; }
(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))) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (boolean_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (boolean_type) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (array_type element: (type_identifier) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (type_identifier) dimensions: (dimensions_expr (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: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal))) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) name: (identifier) arguments: (argument_list (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 (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (null_literal))) consequence: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (parenthesized_expression (ternary_expression condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) consequence: (string_literal) alternative: (string_literal))) right: (cast_expression type: (integral_type) value: (parenthesized_expression (binary_expression left: (character_literal) right: (binary_expression left: (identifier) right: (decimal_integer_literal))))))))) (if_statement condition: (parenthesized_expression (array_access array: (identifier) index: (identifier))) consequence: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal))) right: (array_access array: (identifier) index: (identifier)))))))) (enhanced_for_statement type: (type_identifier) name: (identifier) value: (identifier) body: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (string_literal))))))))