<!DOCTYPE html>
<html>
<head>
<script>

var f1, f2;

function b1()
{
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  f2 = document.getElementById("f2");
  f1.contentWindow.document.write("11");
  f1.contentWindow.history.back();
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}

function b2()
{
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  f2.contentWindow.location.reload();
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}

</script>


</script>
</head>

<body onload="setTimeout(b1, 0);">

<iframe id="f1" src="data:text/html,1"></iframe>
<iframe id="f2" src="data:text/html,2"></iframe>

</body>
</html>