I want to find states with exactly two Os in the name. I tried this:

```
> data(state)
> index=grep('o.*o',state.name)
> state.name[index]
"Colorado"       "North Carolina" "North Dakota"   "South Carolina" "South Dakota"   

```

Problem: there are three Os in "Colorado" and I don't want it. How can I revise my regex?

I also want to do three Os:

```
> data(state)  
> index=grep('o.*o.*o',state.name)  
> state.name[index]
"Colorado"  

```

Is there a simpler way to do this?