How to justify li objects right and left in my navbar

.navbar-nav{
  display: flex;
  justify-content: space-around;
}

<nav class="navbar navbar-expand-lg navbar-light bg-light">
            <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
              <span class="navbar-toggler-icon"></span>
            </button>
            <div class="collapse navbar-collapse" id="navbarNav">
              <ul class="navbar-nav mx-auto">
                <li class="nav-item">
                  <a class="nav-link" href="#">ABOUT US</a>
                </li>
                <a href="#"><img src="images/logo.png"></a>
                <li class="nav-item">
                  <a class="nav-link" href="#">CONTACT</a>
                </li>
              </ul>
            </div>
          </nav>