Welcome to NTHU CS! Before entering out department, you need to play a game with our Department President, Stiff Waist Beast.
The game is very easy, comparing number.
However, Stiff Waist Beast thinks that just compare the value of two number is too boring, so we need to compare the "lucky value" of each number.
Lucky number's formula is: sum of the first and the third digit divided by the sum of the second and the fourth.
Please tell him the lucky value of your number.
You will be given an integer x.
1000 <= x < 10000
Output the lucky value of x to the second decimal place.
Don't forget to print '\n' in the end!