comefrom: <awangdev>218. The Skyline Problem_3.java
code: int parent(int id) {
          if (id == 0) {
              return -1;
          }
          return (id - 1) / 2;
      }
masked: int sample_funcname ( int var_0 ) {
    if ( var_0 == 0 ) {
      return - 1 ;
    }
    return ( var_0 - 1 ) / 2 ;
  }
  