public static void main ( String [ ] args ) {
  Scanner s = new Scanner ( System . in ) ;
  int n = s . nextInt ( ) ;
  boolean [ ] b = new boolean [ n + 1 ] ;
  int res = 0 ;
  for ( int i = 2 ;
  i <= n ;
  i ++ ) b [ i ] = isPrime ( i ) ;
  for ( int i = 3 ;
  i <= n ;
  i ++ ) {
    int c = 0 ;
    for ( int j = 2 ;
    j <= i ;
    j ++ ) {
      if ( b [ j ] && i % j == 0 ) c ++ ;
    }
    if ( c == 2 ) res ++ ;
  }
  System . out . println ( res ) ;
  s . close ( ) ;
}

public static void main ( String [ ] args ) { Scanner s = new Scanner ( System . in ) ; int n = s . nextInt ( ) ; boolean [ ] b = new boolean [ n + 1 ] ; int res = 0 ; for ( int i = 2 ; i <= n ; i ++ ) b [ i ] = isPrime ( i ) ; for ( int i = 3 ; i <= n ; i ++ ) { int c = 0 ; for ( int j = 2 ; j <= i ; j ++ ) { if ( b [ j ] && i % j == 0 ) c ++ ; } if ( c == 2 ) res ++ ; } System . out . println ( res ) ; s . close ( ) ; }
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