A9099 | Routine Problem

Manao has a monitor. The screen of the monitor has horizontal to vertical length ratio $a$ : $b$ . Now he is going to watch a movie. The movie's frame has horizontal to vertical length ratio $c$ : $d$ . Manao adjusts the view in such a way that the movie preserves the original frame ratio, but also occupies as much space on the screen as possible and fits within it completely. Thus, he may have to zoom the movie in or out, but Manao will always change the frame proportionally in both dimensions.

Calculate the ratio of empty screen (the part of the screen not occupied by the movie) to the total screen size. Print the answer as an irreducible fraction $p/q$ .

A single line contains four space-separated integers $a$ , $b$ , $c$ , $d$ ( $1<=a,b,c,d<=1000$ ).

Print the answer to the problem as "p/q", where $p$ is a non-negative integer, $q$ is a positive integer and numbers $p$ and $q$ don't have a common divisor larger than 1.