You are given a code:

def main_solution(x):
    return func_20(func_5('fqmn', 'ieco'), func_15(x))

Can you predict the output of `main_solution("rtna")` 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": "rtna"}, "ref_output": "i\u00aberc\u00bbo\u00abftq\u00bbm\u00abnn\u00bb\u00aba\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_5('fqmn', 'ieco'), func_15(x))", "funcname": "main_solution"}
rule