You are given a code:

def main_solution(x):
    return func_13(func_5('oegg', 'fa'), '_')

Can you predict the output of `main_solution("icsgrdp")` 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": "icsgrdp"}, "ref_output": "f_a_o_e_g_g", "ref_code": "def main_solution(x):\n    return func_13(func_5('oegg', 'fa'), '_')", "funcname": "main_solution"}
rule