You are given a code:

def main_solution(x):
    return (func_4('urnb') + func_20('benym', 'aung'))

Can you predict the output of `main_solution("mvaikg")` 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": "mvaikg"}, "ref_output": "urnbbaeunnygm", "ref_code": "def main_solution(x):\n    return (func_4('urnb') + func_20('benym', 'aung'))", "funcname": "main_solution"}
rule