# Extract integers from ranges

In R, what's an efficient way to extract the integers from ranges?

Let's say I have a matrix of ranges (column1=start, column2=end)

1 5 3 6 10 13

I would like to store the encompassing unique integers of all the ranges in the matrix into an object:

1 2 3 4 5 6 10 11 12 13

This would be applied to a matrix containing ~4 million ranges, so hopefully someone can offer a solution that is somewhat efficient.