It's time for desert at Thanksgiving. You've all gathered at grandma's house, and she's about to start cutting the pumpkin pie. You notice, though, that the same particular routine is always followed:

 - each guest tells her what fraction of the remaining pie they want
 - there are an arbitrary number of relatives present each year
 - you are next to last, since you always sit next to grandpa
 - grandpa is last, and will eat whatever is left
    > however, he should only eat up to 1/8 of the total pie, due to health problems
    > but, if you don't leave him 1/8 of the pie, you probably won't get a good Christmas present

So, you must calculate the fraction of what remains to eat such that 1/8 of the whole pie is left for grandpa. If whatever remains is less than or equal to 1/8, you can 'pass', and grandpa won't hold a grudge.

You must give grandma a fraction (in character format), though. She despises decimals, but loves to simplify fractions, so just ensure that the fraction you provide is close enough to the decimal value.