function [awt,lql] = harbor(as1,as2,ult1,ult2,n)
% awt:        average waiting time
% lql:        longest queue length
% as1, as2 :  minimum and maximum arrival of successive ships
% ult1,ult2:  minimum and maximum unloading time
   if nargin == 0,                                    % the given example
      n   = 5;
      rsa = [20 30 15 120 25];
      rut = [55 45 60  75 80];
   else
      if nargin<5, n = as1; end
      as1  = 15; as2  = 145;
      ult1 = 45; ult2 = 90;
      rsa = round(rand(1,n)*( as2- as1)+ as1);        % random ship arrival
      rut = round(rand(1,n)*(ult2-ult1)+ult1);        % random unload time
   end
   at  = cumsum(rsa);                                 % arrival time
   ss(1) = at(1);
   ql(1) = 0;
   for k = 2:n,
       ss(k) = max( at(k), ss(k-1)+rut(k-1) );        % start service
       ql(k) = sum( at(k) < ss(1:k-1)+rut(1:k-1) );   % queue length
   end
   wt  = ss - at;                                     % wait time
   tih = wt + rut;                                    % time in harbor
   awt = mean(wt);                                    % average wating time
   lql = max(ql);                                     % longest queue length
   clc;
   fprintf('%c',61*ones(1,85));
   fprintf('\n%25s%26s%21s%8s','Random time','Queue','Random','Time');
   fprintf('\n%11s%10s%13s%8s%11s%8s%11s%7s','Ship','between','Arrival',...
           'Start','length at','Wait','unload','in');
   fprintf('\n%11s%15s%6s%10s%11s%8s%10s%11s\n','no.','ship arrival','time',...
           'Service','arrival','time','time','harbor');
   fprintf('%c',45*ones(1,85));
   for k = 1:n,
       fprintf('\n');
       fprintf('%10d',k,rsa(k),at(k),ss(k),ql(k),wt(k),rut(k),tih(k));
   end
   fprintf('\nTotal(if appropriate):%38d\n',sum(wt));
   fprintf('Average(if appropriate):%s%6.2f %9.2f %9.2f\n',...
           blanks(30),mean(wt),mean(rut),mean(tih));
   fprintf('Longest queue length: %s%3d\n',blanks(25),lql);
   fprintf('%c',61*ones(1,85));
   fprintf('\n');