#include <iostream>
#include <fstream>

using namespace std;

ifstream input_stream;
ofstream output_stream;


bool is_palindrome(string s) {
	uint8_t s_len = s.length();

	for (uint8_t i = 0; i < (s_len / 2); i++) {
		if (s[i] != s[s_len - i - 1]) {
			return false;
		}
	}

	return true;
}



int main() {
	input_stream.open("input.txt");
	output_stream.open("output.txt");

	string max_pal, tmp;
	string inp = "";

	// File method:
	while (true) {
		input_stream >> tmp;
		if (tmp == "") {
			break;
		}
		inp += " " + tmp;
		tmp = "";
	}

	uint8_t max_pal_len = 0;

	uint8_t inp_len = inp.length();


	for (uint8_t i = 0; i < (inp_len - 1); i++) {
		for (uint8_t j = inp_len - i; j >= 2; j--) {
			if (j > max_pal_len) {
				string sub = inp.substr(i, j);
				if (is_palindrome(sub)) {
					max_pal_len = j;
					max_pal = sub;
				}
			}
		}
	}


	// File method:
	// if (max_pal_len == 0) {
	// 	output_stream << "Nu se contine" << endl;
	// } else {
	// 	output_stream << max_pal << endl;
	// }
	// Console method:
	if (max_pal_len == 0) {
		cout << "Nu se contine" << endl;
	} else {
		cout << max_pal << endl;
	}

	input_stream.close();
	output_stream.close();
	return 0;
}