Please assist -- Unable to remove '-' character from char vector--

Hi,
I have a char vector with year values. Some cells have single year
value '2001-' and some have range like 1996-2007.
I need to remove hyphen character '-' from all the values within the
character vector named as 'end'. After removing the hyphen I need to
get the last
number from the cells where there are year range values i.e if the
cell has range 1996-2007, the code should return me 2007.

How could I get this done?

 Below are the values within this char vector:

end

[1] "2001-"            "1992-"            "2013-"            "2013-"
          "2013-"            "2013-"
 [7] "2003-"            "2010-"            "2009-"            "1986-"
          "2012-"            "2003-"
[13] "2005-"            "2013-"            "2003-"            "2013-"
          "1993?2007, 2010-" "2012-"
[19] "1984?1992, 1996-" "2015-"            "2009-"            "2000-"
          "2005-"            "1997-"
[25] "2012-"            "1997-"            "2002-"            "2006-"
          "1992-"            "2007-"
[31] "1997-"            "1982-"            "2015-"            "2015-"
          "2010-"            "1996?2007, 2011-"
[37] "2004-"            "1999-"            "2007-"            "1996-"
          "2013-"            "2012-"
[43] "2012-"            "2010-"            "2011-"            "1994-"
          "2014-"

I tried below command--> gsub('[-|,]', '', end)
This did remove all the hyphen character but not from cells having
range year values.Below is the result after executing above command:
As you see hypphen character is removed from single values but not
from ranges. Please guide.

gsub('[-|,]', '', end)

[1] "2001"           "1992"           "2013"           "2013"
  "2013"           "2013"           "2003"
 [8] "2010"           "2009"           "1986"           "2012"
  "2003"           "2005"           "2013"
[15] "2003"           "2013"           "1993?2007 2010" "2012"
  "1984?1992 1996" "2015"           "2009"
[22] "2000"           "2005"           "1997"           "2012"
  "1997"           "2002"           "2006"
[29] "1992"           "2007"           "1997"           "1982"
  "2015"           "2015"           "2010"
[36] "1996?2007 2011" "2004"           "1999"           "2007"
  "1996"           "2013"           "2012"
[43] "2012"           "2010"           "2011"           "1994"
  "2014"

Regards,
Sunny Singha