You are given a code:

def main_solution(x):
    return func_13(func_20('blttpt', 'bspl'), '-')

Can you predict the output of `main_solution("wwvbwgdiyo")` 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": "wwvbwgdiyo"}, "ref_output": "b-b-l-s-t-p-t-l-p-t", "ref_code": "def main_solution(x):\n    return func_13(func_20('blttpt', 'bspl'), '-')", "funcname": "main_solution"}
rule