stepan n pen every day use ith day use pen number on n1th day use pen number 1 n2th use pen number 2 onon work day Monday Saturday inclusive Stepan spend exactly 1 milliliter ink pen use day on Sunday Stepan day rest stend ink pen use day Stepan know current volume ink pen now Monday morning Stepan going use pen number 1 today your task determine pen run ink rest ink leave Stepan use pen accord condition describe