<html>
<head>
<meta charset="windows-1251" />
</head>
<body>
<div id="d"></div>
<script>
check=function(){
while(1) {
var data=prompt()
if(/^[а-яё]+ [а-яё]+ [а-яё]+$/i.test(data)) break
alert("try once again!")
}
d.innerHTML=data
}
check()
</script>
</body>
</html>