You are given a code:

def main_solution(x):
    return func_13(func_5('tgabkz', 'lpaf'), '_')

Can you predict the output of `main_solution("zgbpnajy")` 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": "zgbpnajy"}, "ref_output": "l_p_a_f_t_g_a_b_k_z", "ref_code": "def main_solution(x):\n    return func_13(func_5('tgabkz', 'lpaf'), '_')", "funcname": "main_solution"}
rule