A delicatessan has four service lines, each manned by one server. The food is not particularly good there, so customers who arrive when all servers are busy just decide to go to some other restaurant. Suppose that the times at which customers arrive form a Poisson process with rate 2 per minute, and the duration of a service is exponential with mean 5 minutes, independent of other services and of the arrival process. Find the long-run distribution of the number of busy servers.