How to obtain the chat_id of a private Telegram channel

I found the way to write in private channels.

1. You should convert it to public with some @channelName

2. Send a message to this channel through the Bot API:

   https://api.telegram.org/bot111:222/sendMessage?chat_id=@channelName&text=123

3. As the response, you will get information with chat_id of your channel.

   {
     "ok" : true,
     "result" : {
       "chat" : {
         **"id" : -1001005582487,**
         "title" : "Test Private Channel",
         "type" : "channel"
       },
       "date" : 1448245538,
       "message_id" : 7,
       "text" : "123ds"
     }
   }
   

4. Now you can convert the channel back to private (by deleting the channel’s link) and send a message directly to the chat_id “-1001005582487”:

   https://api.telegram.org/bot111:222/sendMessage?chat_id=-1001005582487&text=123