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Thank you.

\documentclass[12pt]{article}
\usepackage[latin1]{inputenc}
\usepackage[italian]{babel}
\usepackage[a4paper,top=1.8cm,bottom=1.8 cm,left=2.5 cm,right=2.5 cm,]{geometry}%includehead,includefoot
\usepackage{amssymb,latexsym}
\usepackage{amsmath}
\usepackage{mathrsfs}
\usepackage{mathabx ...

I have accidentally typesetted some keys, so the symbol ° (Celsius degree) has been replaced by "xB0".
How can I solve this problem?
Thank you