+\usepackage[latin1]{inputenc}
+\usepackage[T1]{fontenc}
+\usepackage[english]{babel}
+\usepackage{amsmath,amssymb,latexsym,eufrak,euscript}
+\usepackage{pstricks,pst-node,pst-coil}
+
+
+\usepackage{url,tikz}
+\usepackage{pgflibrarysnakes}
+
+\usepackage{multicol}
+
+\usetikzlibrary{arrows}
+\usetikzlibrary{automata}
+\usetikzlibrary{snakes}
+\usetikzlibrary{shapes}
+