You are given a code:

def main_solution(x):
    return func_13(func_20('vsgndu', 'zrjfem'), '-')

Can you predict the output of `main_solution("gxj")` 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": "gxj"}, "ref_output": "v-z-s-r-g-j-n-f-d-e-u-m", "ref_code": "def main_solution(x):\n    return func_13(func_20('vsgndu', 'zrjfem'), '-')", "funcname": "main_solution"}
rule