comefrom: <gouthampradhan>math_CountPrimes_1.java
code: public int countPrimes(int n) {
      if (n == 0 || n == 1 || n == 2) return 0;
      else if (n == 3) return 1;
      BitSet set = new BitSet();
      n = n - 1;
      int sqRt = (int) Math.sqrt(n);
      int count = n;
      for (int i = 2; i <= sqRt; i++) {
        if (!set.get(i)) {
          for (int j = 2; (i * j) <= n; j++) {
            if (!set.get(i * j)) {
              count--;
              set.set(i * j);
            }
          }
        }
      }
      return count - 1;
    }
masked: public int sample_funcname ( int var_0 ) {
    if ( var_0 == 0 || var_0 == 1 || var_0 == 2 ) return 0 ;
    else if ( var_0 == 3 ) return 1 ;
    BitSet set = new BitSet ( ) ;
    var_0 = var_0 - 1 ;
    int var_9 = ( int ) Math . sqrt ( var_0 ) ;
    int var_10 = var_0 ;
    for ( int var_11 = 2 ;
    var_11 <= var_9 ;
    var_11 ++ ) {
      if ( ! set . get ( var_11 ) ) {
        for ( int var_13 = 2 ;
        ( var_11 * var_13 ) <= var_0 ;
        var_13 ++ ) {
          if ( ! set . get ( var_11 * var_13 ) ) {
            var_10 -- ;
            set . set ( var_11 * var_13 ) ;
          }
        }
      }
    }
    return var_10 - 1 ;
  }
  