## [QBIC](https://drive.google.com/drive/folders/0B0R1Jgqp8Gg4cVJCZkRkdEthZDQ), 25 bytes

    :[0,a,sgn(a)|A=A+!b$]?_lA

Explanation:

    :[0,a     Read 'a' from the cmd line, start a FOR loop from 0 to 'a'
    ,sgn(a)|  with incrementer set to -1 for negative ranges and 1 for positive ones
    A=A+!b$   Add a string cast of each iteration (var 'b') to A$
    ]         NEXT
    ?_lA      Print the length of A$