1차수정

+var express = require('express');
+var app = express();
+var server = app.listen(3000,function(){
+    console.log("Express server has started on port 3000")
+})
+
+app.get('/',function(req,res){
+    res.send("hello");
+    // res.sendFile('index.html', { root: __dirname });
+});
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