1
Face this has in the documentation... It is called button-group https://getbootstrap.com/docs/4.0/components/button-group/
Application example
<link rel="stylesheet" type="text/css" media="screen" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" />
<div class="container">
<div class="row">
<div class="col">
<div class="btn-group btn-group-lg" role="group" aria-label="Large button group">
<button type="button" class="btn btn-secondary">4</button>
<!-- <button type="button" class="btn">Middle</button> -->
<input type="text" class="border px-2 border-right-0">
<button type="button" class="btn border border-left-0">←</button>
</div>
</div>
</div>
</div>