How to get values of the choosen keys in a nested json

I have a json that looks like this

dict = { "a1": { "b1" : 1 , "b2" ; { "c1" : 24, "c2" : 25}, "b3" : { "c3" : 45, "c4" : 1, "c5" : 4} }, "a2" : 4}

i want to give arrays like so FIRSTS = ["a1"] SECONDS = ["b1", "b3"] THIRDS = ["c3"]

which would print this : [b1 : 1], [c3 : 45]

i have written this code

message = ""
for first in FIRSTS:
  if first in json_object:
    if isinstance(json_object[first], dict):
      for second in SECONDS:
        if second in json_object[first]:
          if isinstance(json_object[first][second], dict):
            for third in THIRDS:
              if third in json_object[first][second]:
                message = message + f"[{third} : {json_object[first][second][third]}], "
              else:
                message = message + f"[{third} not found], "
          else:
            message = message + f"[{second} : {json_object[first][second]}], "
        else:
          message = message + f"[{second} not found], "
    else:
      message = message + f"[{first} : {json_object[first]}], "
  else:
    message = message + f"[{first} not found], "

print(message[:-2])

But I'd like a better way to do it

EDIT: Hey i'm editing for clarification, so i want to print the key value pairs, when the value is not a sub json. So in my code i check for every key in FIRSTS, if it's value is a json, if it is i check if it has a key that is equal to a key in SECONDS, and repeat with THIRDS, and if the value of the key is not a json i print the key value pair.

EDIT2: Someone asked for an edit on the input, so i wanted to precise the input could be anything even keys that might not appear in the json, that's why i do all the checking in my code

source https://stackoverflow.com/questions/75770081/how-to-get-values-of-the-choosen-keys-in-a-nested-json