int main(){
	string a, b, c, buf;
	cin >> a >> b >> c;

	if (a.length() <= b.length() and a.length() <= c.length()) buf = a;
	else if (b.length() <= a.length() and b.length() <= c.length()) buf = b;
	else buf = c;
	vector<string> vec;

	for (int i = 1; i <= buf.length(); i++) {
		ll tt = 0;
		for (int l = 0; l < buf.length() - i + 1; l++) {
			string ar;
			for (int j = 0; j < i; j++) { ar = ar + buf[l + j]; }
			if (a.find(ar) != string::npos && b.find(ar) != string::npos && c.find(ar) != string::npos) {
				vec.push_back(ar);
				tt = 1;
				break;
			}
		}
		if (tt == 0) {
			break;
		}
	}
	cout << vec[vec.size() - 1];
}