You are given a code:

def main_solution(x):
    return ('umrp' + 'jfz')

Can you predict the output of `main_solution("kzkwtxdnk")` 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": "kzkwtxdnk"}, "ref_output": "umrpjfz", "ref_code": "def main_solution(x):\n    return ('umrp' + 'jfz')", "funcname": "main_solution"}
rule