Knowing the number of exons in a range

Hi

I have copy number segment from exome seq like

> head(CN)
# A tibble: 6 x 6
  file              Chromosome   Start      End Total_CN Minor_CN
  <chr>             <chr>        <int>    <int>    <int>    <int>
1 sample1            51479   817980        2        0

How I know how many exones are in the range of End-Start ?