需要帮助为elb设置cloudwatch警报

Need help setting up cloudwatch alarm for elb

I am trying to create two cloudwatch alarm on my Elastic LoadBalancer. Suppose there is 3 instance attached to my elb.

If one instance goes unhealthy then I should trigger an alarm saying it's a WARNING and if all instance is unhealthy then I should trigger an alarm saying it's a CRITICAL.

I am experimenting with cloud watch metrics MAX, MIN, AVG and I am not getting right condition to put into.

This is what I am doing right now.

For CRITICAL if maximum no of healthy host < 1 .

This works but is taking a long time for creating that alarm.

For WARNING if maximum no of unhealthy host > 0.

I dont have much confidence in this because I am not able to verify this .