Well, you could add two string variables, str_j and str_J_1 to take the place of the integers, j and (j+1).
Then you could could add the lines:
str_j = CStr(j)
str_J_1 = CStr(J+1)
I don't remember if CStr() allows you to have an expression in its parenthesis, you may need to add
an intermediate variable.