# Jolf, 13 bytes

    ΆFi liγhj_γgi

A tranpilation of the JavaScript answer.

Explanation:

    ΆFi liγhj_γgi
    Ά             ternary add
     Fi            i[0],
       `li         i sliced
          γhj       γ = j + 1
             _γ     to -γ
               gi  and the last of i

[Try it here!](http://conorobrien-foxx.github.io/Jolf/#code=zoZGaSBsac6zaGpfzrNnaQ)

A more interesting post-question version:

     ΆFi]ihjYgi