\documentclass[dvips,11pt]{article}
\usepackage{amsmath,amssymb,amsfonts}
\usepackage[latin1]{inputenc}
\usepackage{./vil}
%\usepackage[dvips]{graphicx,color}
\usepackage{graphicx,color}

\begin{document}

N\textsuperscript{\underline{o}}


1\textsuperscript{\underline{o}}

2\textsuperscript{\underline{o}}

2\textsuperscript{\underline{a}}

\end{document}









