How to write a regular expression that 's match a list then spilt it

#include<iostream>
#include<regex> 
#include<string.h> 
using namespace std;
void main()
{
	string E1 ;
	cout << "Enter a sentence E1 : " << endl;
	getline(cin, E1);

	regex r("\\[+ [a-z]*||([A-Za-z]*||(\\[+\\] )+\\, +\\]");
	bool b = regex_match(E1, r);

	cout <<( b ? "T":"f")<< endl;
	system("pause");
}

input: [A,nana,12,[],[as,45,Ad]] 
output:match