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<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>Document</title>
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    <style>
        .b{
            border: solid 1px black;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="row">
            <div class="col-md-4 b">
                <img class="img-fluid" src="jeju.jpg" alt="">
            </div>
            <div class="col-md-4 b">
                <img class="img-fluid rounded-circle" src="jeju.jpg" alt="">
            </div>
            <div class="col-md-4 b">
                <img class="img-fluid img-thumbnail" src="jeju.jpg" alt="">
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</body>
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