You are given a code:

def main_solution(x):
    return func_13(func_5('mvkozc', 'keb'), '-')

Can you predict the output of `main_solution("crffmcv")` 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": "crffmcv"}, "ref_output": "k-e-b-m-v-k-o-z-c", "ref_code": "def main_solution(x):\n    return func_13(func_5('mvkozc', 'keb'), '-')", "funcname": "main_solution"}
rule