public static void main ( String [ ] args ) {
  Scanner input = new Scanner ( System . in ) ;
  int n = input . nextInt ( ) ;
  int k = input . nextInt ( ) ;
  input . nextLine ( ) ;
  int [ ] x = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) x [ i ] = input . nextInt ( ) ;
  int count = 1 ;
  int d = k ;
  boolean flag = true ;
  for ( int i = 1 ;
  ( i < n ) && flag ;
  i ++ ) {
    d -= x [ i ] - x [ i - 1 ] ;
    if ( d < 0 ) flag = false ;
    else if ( i != n - 1 && d >= ( x [ i + 1 ] - x [ i ] ) ) {
      continue ;
    }
    else {
      count ++ ;
      d = k ;
    }
  }
  count -- ;
  if ( flag ) System . out . println ( count ) ;
  else System . out . println ( "-1" ) ;
}

public static void main ( String [ ] args ) { Scanner input = new Scanner ( System . in ) ; int n = input . nextInt ( ) ; int k = input . nextInt ( ) ; input . nextLine ( ) ; int [ ] x = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) x [ i ] = input . nextInt ( ) ; int count = 1 ; int d = k ; boolean flag = true ; for ( int i = 1 ; ( i < n ) && flag ; i ++ ) { d -= x [ i ] - x [ i - 1 ] ; if ( d < 0 ) flag = false ; else if ( i != n - 1 && d >= ( x [ i + 1 ] - x [ i ] ) ) { continue ; } else { count ++ ; d = k ; } } count -- ; if ( flag ) System . out . println ( count ) ; else System . out . println ( " - 1" ) ; }
(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)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (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: (array_creation_expression type: (integral_type) 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: (identifier)) update: (update_expression (identifier)) body: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (identifier))) (local_variable_declaration type: (boolean_type) declarator: (variable_declarator name: (identifier) value: (true))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (expression_statement (assignment_expression left: (identifier) right: (false))) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (array_access array: (identifier) index: (identifier))))))) consequence: (block (continue_statement)) alternative: (block (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (identifier)))))))) (expression_statement (update_expression (identifier))) (if_statement condition: (parenthesized_expression (identifier)) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier)))) alternative: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))))))