h1, h2, h3, h4 {
    text-align: center
    }
.ctr {
    text-align: center
    }
a:link {
    color: blue;
    text-decoration: none
    }
link {
    color: blue;
    text-decoration: none
    }
a:visited {
    color: blue;
    text-decoration: none
    }
a:hover {
    color: red
    }
pre {
    font-size: 10pt
    }