Sentimental Analysis from Twitter using R : I am getting below error while executing my code.

**Error while entering PIN** 

**Error Message :
Error in function (type, msg, asError = TRUE)  : 
Could not resolve host:**

    download.file(url = 'http://curl.haxx.se/ca/cacert.pem', destfile = 'cacert-pem')
        oauth_endpoint(authorize = "https://api.twitter.com/oauth",
                       access = "https://api.twitter.com/oauth/access_token")
        reqURL <- 'https://api.twitter.com/oauth/request_token'
        accessURL <- 'https://api.twitter.com/oauth/access_token'
         authURL <- 'https://api.twitter.com/oauth/authorize'
        consumerKey <- "xxxxx"
        consumerSecret = "xxxx"
        accesstoken = "xxxx"
        accesssecret = "xxxxxv"
        Cred <- OAuthFactory$new(consumerKey = consumerKey,
                                 consumerSecret=consumerSecret,
                                 requestURL=reqURL,
                                 authURL=authURL)
        
        Cred$handshake(cainfo = system.file('CurlSSL','cacert.pem', package = 'RCurl'))
