I think my program is right, but it got WA, why? Could you help me?

Here is my code:

const
  maxnum=1000000000;
var
    best,i,j,dis,cost:cardinal;
  begin
    for i:=s+1 to t do begin
      best:=maxnum;
      for j:=i-1 downto s do begin
        if f[j]=maxnum then continue;
        dis:=abs(len[i]-len[j]);
        if dis>l[3] then break
          else if dis>l[2] then cost:=c[3]
            else if dis>l[1] then cost:=c[2]
              else cost:=c[1];
        if cost>=maxnum then break
          else if cost+f[j]<best then best:=cost+f[j];
      end;
      if best<maxnum then f[i]:=best;
    end;
    writeln(f[t]);
  end;

begin
  for i:=1 to 3 do read(l[i]);
  for i:=1 to 3 do read(c[i]);
  readln(n);
  readln(s,t);
  if s>t then begin
    i:=s;
    s:=t;
    t:=i;
  end;
  if s=t then begin writeln(0);halt;end;
  for i:=2 to t do begin
    read(len[i]);
    f[i]:=maxnum;
  end;
  f[s]:=0;
  solve;
end.