You are given a code:

def main_solution(x):
    return (func_20(x, 'ldioi') + func_15('spea'))

Can you predict the output of `main_solution("zzifnxotpf")` 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": "zzifnxotpf"}, "ref_output": "zlzdiifonixotpf\u00abs\u00bb\u00abp\u00bb\u00abe\u00bb\u00aba\u00bb", "ref_code": "def main_solution(x):\n    return (func_20(x, 'ldioi') + func_15('spea'))", "funcname": "main_solution"}
rule