poj/poj2017.pas

   1 var
   2 n,s,t,p,i,sum:longint;
   3
   4 begin
   5    readln(n);
   6    while n<>-1 do
   7    begin
   8       p:=0; sum:=0;
   9       for i:=1 to n do
  10       begin
  11          readln(s,t);
  12          sum:=sum+s*(t-p);
  13          p:=t;
  14       end;
  15       writeln(sum,' miles');
  16       readln(n);
  17    end;
  18 end.