private int checkArguments(String[] args, Airport startPort) {
    int retu = 0;

    if((args[0]).equals("-e")) {
      retu = 1;
      if(args.length != 1) {
        return -1;
      }
/*    } else if((args[0]).equals("-graham")) {
      retu = 3;
      if(args.length != 1) {
        return -1;
      }*/
    } else if((args[0]).equals("-oneway")) {
      retu = 4;
      if(args.length != 1) {
        return -1;
      }
    } else if((args[0]).equals("-kml")) {
      retu = 2;
      if(args.length != 1) {
        return -1;
      }
    } else if((args[0]).equals("-prim")) {
      retu = 5;
      if(args.length != 1) {
        return -1;
      }
    }
    return retu;
  }