AWS:EC2 connect to RDS via ssh, error:Access denied

I'm following this post to try connect ec2 instance to rds.

when I reach the last step: PROMPT> mysql -h -P 3306 -u -p

I type this in my ssh ,but I get a access denied error: error 1045(28000): Access denied for...

as shown below(coverd some personal info)

what is the problem?anyone have any idea?

Thanks in advance.