count number of stop words in R

Hi all,

Is there a way in R to count the number of stop words (English) of a string using tm package?

str="Mhm . Alright . There's um a young boy that's getting a cookie jar . And it he's uh in bad shape because uh the thing is falling over . And in the picture the mother is washing dishes and doesn't see it . And so is the the water is overflowing in the sink . And the dishes might get falled over if you don't fell fall over there there if you don't get it . And it there it's a picture of a kitchen window . And the curtains are very uh distinct . But the water is still flowing . 

255 Levels: A boy's on the uh falling off the stool picking up cookies . The girl's reaching up for it . The girl the lady is is drying dishes . The water is uh running over uh from the sink into the floor . The window's opened . Dishes on the on the counter . She's outside ."

Thanks for any help!
Elahe