Default password after installing in CentOS7

I’m new with Percona Server.
I always have problem with accessing into Percona Server 5.7 after I install it in CentOS 7.
After start mysql at the first time.
Accessing into mysql always show ERROR 1045 (28000): Access denied for user ‘root’@‘localhost’ (using password: NO).
And I have no idea about what is the password? Because I have just install it.
Please help!

In mysqld.log file you’ll find a line similar to this:
[root@kz ~]# cat /var/log/mysqld.log |grep generated
2016-05-01T10:52:09.019006Z 1 [Note] A temporary password is generated for root@localhost: *******
That’s your temporary password which you can use to login.
To further secure your installation run /usr/bin/mysql_secure_installation