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<html>
<head>
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  <title>Diagonal Mirror Pyramid</title>
</head>
<body>
  <pre id="out"></pre>
  <script>
    const rows = 5;
    let result = "";

    for (let i = 1; i <= rows; i++) {
      let line = "";

      for (let j = rows; j >= 1; j--) {
        line += (i === j) ? i : " ";
      }

      for (let k = 2; k <= rows; k++) {
        line += (i === k) ? i : " ";
      }

      result += line.replace(/\s+$/, "") + "\n";
    }

    document.getElementById("out").textContent = result;
  </script>
</body>
</html>

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