<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Flex Header</title>
<link rel="stylesheet" href="solution.css">
</head>
<body>
<div class="header">
<div class="left-links">
<ul>
<li><a href="#">ONE</a></li>
<li><a href="#">TWO</a></li>
<li><a href="#">THREE</a></li>
</ul>
</div>
<div class="logo">LOGO</div>
<div class="right-links">
<ul>
<li><a href="#">FOUR</a></li>
<li><a href="#">FIVE</a></li>
<li><a href="#">SIX</a></li>
</ul>
</div>
</div>
</body>
</html>