You are given a code:

def main_solution(x):
    return func_5(func_20('xvl', x), 'mbu')

Can you predict the output of `main_solution("xncsljwzn")` 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": "xncsljwzn"}, "ref_output": "mbuxxvnlcsljwzn", "ref_code": "def main_solution(x):\n    return func_5(func_20('xvl', x), 'mbu')", "funcname": "main_solution"}
rule