Write a program to output letter grades A$,$ B$,$ C$,$ D$,$ F corresponding to the scores

lying between $90$ and $100,80$ and $89,70$ and $79,60$ and $69($inclusive of the end points$).$ For

instance if the overall aggregate scores of a student lie between these slabs, say like $89\mathrm{.}5$ or $89\mathrm{.}4,$

consider rounding up or down if the fractional part is greater than or equal to $5,$ or less than $5.$ If

the user inputs numbers less than zero or greater than $100,$ print $$Error$!$ Try again!$$