I have recently subscribed to a telegram bot that sends me messages for the future contests on codeforces, codechef and topcoder.
I found some contests which don't appear on the "Contest" tab but showing that they will start in a day or an hour. And also I cant register for those. What are they? The links to the contests are below:
http://mirror.codeforces.com/contests/769
http://mirror.codeforces.com/contests/780