public static void main ( String [ ] args ) {
  Scanner scanner = new Scanner ( System . in ) ;
  int n = scanner . nextInt ( ) ;
  long [ ] [ ] rooms = new long [ n ] [ 3 ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    rooms [ i ] [ 0 ] = scanner . nextInt ( ) - 1 ;
  }
  scanner . close ( ) ;
  long output = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int pointer = ( int ) rooms [ i ] [ 0 ] ;
    rooms [ i ] [ 2 ] = output ;
    long portalValue = 2 ;
    for ( int j = pointer ;
    j < i ;
    j ++ ) {
      portalValue = ( portalValue + rooms [ j ] [ 1 ] ) % 1000000007 ;
    }
    rooms [ i ] [ 1 ] = portalValue ;
    output = ( output + portalValue ) % 1000000007 ;
  }
  System . out . println ( output ) ;
}

public static void main ( String [ ] args ) { Scanner scanner = new Scanner ( System . in ) ; int n = scanner . nextInt ( ) ; long [ ] [ ] rooms = new long [ n ] [ 3 ] ; for ( int i = 0 ; i < n ; i ++ ) { rooms [ i ] [ 0 ] = scanner . nextInt ( ) - 1 ; } scanner . close ( ) ; long output = 0 ; for ( int i = 0 ; i < n ; i ++ ) { int pointer = ( int ) rooms [ i ] [ 0 ] ; rooms [ i ] [ 2 ] = output ; long portalValue = 2 ; for ( int j = pointer ; j < i ; j ++ ) { portalValue = ( portalValue + rooms [ j ] [ 1 ] ) % 1000000007 ; } rooms [ i ] [ 1 ] = portalValue ; output = ( output + portalValue ) % 1000000007 ; } System . out . println ( output ) ; }
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