How can I change a variable in Ansys APDL command with the help of Matlab?

Hi, I would like to run several APDL input files in a loop. This is the line, that runs the input file from Matlab. In every step I want to change input.inp to input_1.inp, input_2.inp etc...

if true
!"C:\Program Files\ANSYS Inc\v172\ANSYS\bin\winx64\ansys172.exe"  -b -j file -mpi INTELMPI -np 4 -i input.inp -o solve.out
end

So the new code line should look like this:

if true
  !"C:\Program Files\ANSYS Inc\v172\ANSYS\bin\winx64\ansys172.exe"  -b -j file -mpi INTELMPI -np 4 -i input_1.inp -o solve.out
end

Is it possible to create a variable with the new filename and somehow putting it into this code? Could you suggest any solution to this problem?

Thank you in advance,

Anna