You are given a code:

def main_solution(x):
    return func_13(('vcstl' + x), '-')

Can you predict the output of `main_solution("ctuoioagv")` 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": "ctuoioagv"}, "ref_output": "v-c-s-t-l-c-t-u-o-i-o-a-g-v", "ref_code": "def main_solution(x):\n    return func_13(('vcstl' + x), '-')", "funcname": "main_solution"}
rule