You are given a code:

def main_solution(x):
    return func_20(func_1('kjnizf', 4), func_15('lurn'))

Can you predict the output of `main_solution("ftk")` 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": "ftk"}, "ref_output": "k\u00abjln\u00bbi\u00abzuf\u00bbk\u00abjrn\u00bbi\u00abznf\u00bbkjnizfkjnizf", "ref_code": "def main_solution(x):\n    return func_20(func_1('kjnizf', 4), func_15('lurn'))", "funcname": "main_solution"}
rule