How to plot SOM results in Cluster form or How to check how many cluster are formed using self-organizing map

Hello i hope you are doing well. I am using Neural Net Clustering app to cluster Fisher iris Dataset.

I want to see the clustering Result or How to check how may cluster are formed using self-organizing map

load fisheriris.mat
P=meas;
net=selforgmap([10 10]);
net=configure(net,P);
net=train(net,P);
view(net);
y=net(P);
classes=vec2ind(y);