/* broken, i don't understand c++ templates */

#include <cctype>
#include <iostream>
#include <memory>
#include <stdexcept>
#include <string>
#include <variant>
#include <vector>
using namespace std;

struct El
{
	variant<unique_ptr<vector<El>>, int> v;

	template<typename T>
	El(T v)
	{
		this->v = v;
	}

	void
	print()
	{
		if (holds_alternative<int>(v)) {
			cout << get<int>(v);
		} else {
			cout << "[";
			for (auto &e : *get<unique_ptr<vector<El>>>(v)) {
				e.print();
				cout << ",";
			}
			cout << "]";
		}
	}
};

El
parse(istream &s)
{
	char c = s.get();
	if (c == '[') {
		auto v = make_unique<vector<El>>();
		for (;;) {
			v->push_back(parse(s));
			do {
				c = s.get();
			} while (isspace(c));
			if (c == ']') break;
			if (c != ',') throw invalid_argument("array sep");
		}
		return El(move(v));
	}
	if (isdigit(c)) {
		int v;
		s.putback(c);
		s >> v;
		return El(v);
	}
	throw invalid_argument("unexpected char");
}

int
main()
{
	El a = parse(cin);
	a.print();
}