I’ve been using LaTeX for a couple of small projects recently and I had some trouble figuring out how to make the accented characters as well as stuff like ‘Ç’ render correctly in the end product. After some mucking about I learned that we have to use three extra packages so everything shows up nicely in the end. It probably works just as well for other languages but you may want to refer to the documentation. Here are the packages you have to use:

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\usepackage[portuguese]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}