#ifndef S0017_LETTER_COMBINATIONS_OF_A_PHONE_NUMBER_HPP
#define S0017_LETTER_COMBINATIONS_OF_A_PHONE_NUMBER_HPP

#include <vector>
#include <string>
#include <unordered_map>

using namespace std;

class S0017 {
 public:
  vector<string> letterCombinations(string digits);
};

#endif