You are given a code:

def main_solution(x):
    return func_13(('hqvfkb' + 'kmi'), '-')

Can you predict the output of `main_solution("xrfaawtx")` without writing any code? Please reason and put your final answer in the following json format: {"output": <your output>}, where <your output> should be the final string.
user
{"ref_input": {"x": "xrfaawtx"}, "ref_output": "h-q-v-f-k-b-k-m-i", "ref_code": "def main_solution(x):\n    return func_13(('hqvfkb' + 'kmi'), '-')", "funcname": "main_solution"}
rule