Update 500px difficulty (#307)
Update 500px difficulty (#307)

Update 500px difficulty to hard, based on input given on issue #306

jdm-contrib/justdelete.me,tupaschoal/justdelete.me,jdm-contrib/justdelete.me,jdm-contrib/justdelete.me,tupaschoal/justdelete.me,jdm-contrib/justdelete.me,tupaschoal/justdelete.me,tupaschoal/justdelete.me