m = m + 1 can be m += 1

and

total = total + tenttotal + ref[roman[m]] - negtotal can be total += tenttotal + ref[roman[m]] - negtotal

You can simplify foo = foo + ... to just foo += ....

For example you can simplify the following two lines:

m = m + 1

m += 1

total = total + tenttotal + ref[roman[m]] - negtotal

total += tenttotal + ref[roman[m]] - negtotal

@TheCount Do you know about the shorthand "+" in general programming and python? E.g.,

m = m + 1 can be m += 1

and

total = total + tenttotal + ref[roman[m]] - negtotal can be total += tenttotal + ref[roman[m]] - negtotal

m = m + 1 can be m += 1

and

total = total + tenttotal + ref[roman[m]] - negtotal can be total += tenttotal + ref[roman[m]] - negtotal