Why doesn't mysql work immediately after installation?

Question

MySQL

Installed mysql maria-db
sudo apt-get install mariadb-server mariadb-client
further, configured
sudo mysql_secure_installation
all the questions, answered positively,
set the password to 'root',
run it from the terminal, mysq -u root -p root
output

ERROR 1698 (28000): Access denied for user 'root'@'localhost'

what did I miss?
thanks in advance.

Answer 1

extra space
mysql -u root -proot