n等于19，是质数
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<title>Document</title>
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<script>
var n = 19
var iszhishu =true
for(var i=2;i<n;i++){
if(n%i===0){
iszhishu = false
}
}
if(iszhishu){
console.log("是")
}else{
console.log("不是")
}
</script>
</body>
</html>
