tour.pas

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program E1_9; {tour}
 var distance,capacity,km:real;
     ic,minc:longint;
     n:byte;
     station:array[0..50,1..2] of real;
 procedure init;
  var i:byte; c:real;
  begin
   assign(input,'tour.in');
   reset(input);
   readln(input,distance);
   readln(input,capacity,km,c,n);
   ic:=round(c*100);
   for i:=1 to n do
    begin
     readln(input,station[i,1],station[i,2]);
     station[i,2]:=station[i,2]*100;
    end;
   close(input);
  end;

  procedure search;
   procedure drive(stop:byte;cost:longint);
   var num:byte;
   begin
    if station[stop,1]+capacity*km>=distance then
    begin
     if cost<minc then minc:=cost;
     exit;
    end;
    num:=stop+1;
    while (num<n) and (station[num+1,1]<=station[stop,1]+capacity*km) and (station[num,1]<=station[stop,1]+capacity*km/2) do
    inc(num);
    if(num=n) or (station[num+1,1]>station[stop,1]+capacity*km) then
     drive(num,cost+2000+round((station[num,1]-station[stop,1])/km*station[num,2]));
    while (num<=n) and (station[num,1]<=station[stop,1]+capacity*km/2) do
    inc(num);
    while (num<=n) and (station[num,1]<=station[stop,1]+capacity*km) do
     begin
      drive(num,cost+2000+round((station[num,1]-station[stop,1])/km*station[num,2]));
      inc(num);
     end;
   end;
   begin {search}
    minc:=maxlongint;
    drive(0,ic);
   end;

  procedure print;
  begin
  assign(output,'tour.out');
  rewrite(output);
  writeln(output,minc/100:0:1);
  close(output);
  end;

  begin
  init;
  search;
  print;
  end.