Hi, I have been trying to loop over some file names.

I have something like this:

foreach s of num 2007/2015{
clear all
use "$path/Matricula Universitaria/`s'_1C.dta", clear
merge m:m mrun using "$path/Matricula Universitaria/`s+1'_2A.dta", keep(match master) force
}


For instance, I want to match the database 2007_1C with the 2008_1A but I can't get the `s+1' to work. If I do that, it merges the 2007_1C with the 2007_1A

If I write
merge m:m mrun using "$path/Matricula Universitaria/`s'+1_2A.dta", keep(match master) force


I get the following error message:
file C:.../Matricula Universitaria/2007+1_2A.dta not found

Any help is welcome! Thanks