You are given a code:

def main_solution(x):
    return func_13(func_20('cfteek', 'ckzyos'), '-')

Can you predict the output of `main_solution("wqivvvgrb")` 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": "wqivvvgrb"}, "ref_output": "c-c-f-k-t-z-e-y-e-o-k-s", "ref_code": "def main_solution(x):\n    return func_13(func_20('cfteek', 'ckzyos'), '-')", "funcname": "main_solution"}
rule