Winnie Leung   F.4CA  (22)
HW3(II) ----  BK2 P.17 #5
program amount(input, output);
uses wincrt;
var  n1, n2, n3: real;
     r1, r2 :string ;
     a1, a2 :string;
     ep1, ep2 :integer;
begin
   repeat      
     write('Please enter the first amount: ');
     readln(a1);
     if copy(a1,1,1) <>'$' then
     writeln('Invalid input.')
   until      
     copy(a1, 1, 1) = '$';
 r1 := copy (a1,2,6);
   repeat
     write('Please enter the second amount: ');
     readln(a2);
     if copy(a2,1,1) <>'$' then
     writeln('Invalid input.')
   until
     copy(a2,1,1) = '$';
 r2 := copy (a2,2,6);
 val(r1, n1, ep1);
 val(r2, n2, ep2);
 n3:= n1 + n2;
 writeln(a1, ' + ', a2, ' = ','$', n3:6:2)
end.