public static void main ( String [ ] args ) throws Exception {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  String [ ] array ;
  array = br . readLine ( ) . split ( " " ) ;
  int n = Integer . parseInt ( array [ 0 ] ) ;
  int l = Integer . parseInt ( array [ 1 ] ) ;
  ArrayList < Integer > list = new ArrayList < Integer > ( ) ;
  for ( String str : br . readLine ( ) . split ( " " ) ) {
    list . add ( Integer . parseInt ( str ) ) ;
  }
  int index = - 1 ;
  for ( int i = 0 ;
  i < n - 1 ;
  i ++ ) {
    if ( list . get ( i ) + list . get ( i + 1 ) >= l ) {
      index = i ;
      break ;
    }
  }
  if ( index < 0 ) {
    System . out . println ( "Impossible" ) ;
  }
  else {
    System . out . println ( "Possible" ) ;
    for ( int i = 0 ;
    i < index ;
    i ++ ) {
      System . out . println ( i + 1 ) ;
    }
    for ( int i = n - 1 ;
    index < i ;
    i -- ) {
      System . out . println ( i ) ;
    }
  }
}

public static void main ( String [ ] args ) throws Exception { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; String [ ] array ; array = br . readLine ( ) . split ( " ▁ " ) ; int n = Integer . parseInt ( array [ 0 ] ) ; int l = Integer . parseInt ( array [ 1 ] ) ; ArrayList < Integer > list = new ArrayList < Integer > ( ) ; for ( String str : br . readLine ( ) . split ( " ▁ " ) ) { list . add ( Integer . parseInt ( str ) ) ; } int index = - 1 ; for ( int i = 0 ; i < n - 1 ; i ++ ) { if ( list . get ( i ) + list . get ( i + 1 ) >= l ) { index = i ; break ; } } if ( index < 0 ) { System . out . println ( " Impossible " ) ; } else { System . out . println ( " Possible " ) ; for ( int i = 0 ; i < index ; i ++ ) { System . out . println ( i + 1 ) ; } for ( int i = n - 1 ; index < i ; i -- ) { System . out . println ( i ) ; } } }
(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 (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))))) (local_variable_declaration type: (array_type element: (type_identifier) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) name: (identifier) arguments: (argument_list (string_literal))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (decimal_integer_literal)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (decimal_integer_literal)))))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (type_identifier))) arguments: (argument_list)))) (enhanced_for_statement type: (type_identifier) name: (identifier) value: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) name: (identifier) arguments: (argument_list (string_literal))) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (unary_expression operand: (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: (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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))) right: (identifier))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (identifier))) (break_statement))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) 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)))) (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 (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))))))