#include <algorithm>
#include <vector>
#include <iostream>
#include <map>

struct card {
  char rank;
  char color;
  bool used;
};	

//std::vector<card> cards;
int num_cards;
std::map<char ,int> color_count;
std::map<char, int> rank_count;

bool try_next(card last, std::vector<card> cards) {
  if (num_cards == 0) return true;
  
  
  std::sort(cards.begin(), cards.end(), [&](const card& l, const card& r){
      auto l_possible = color_count[l.color] + rank_count[l.rank];
      auto r_possible = color_count[r.color] + rank_count[r.rank];
      return l_possible < r_possible;
  });
  for (auto& c : cards){
    if (!c.used && (last.color == 0 || c.color == last.color || c.rank == last.rank)) {
      color_count[c.color]--;
      rank_count[c.rank]--;
      c.used = true;
      num_cards--;
      if (try_next(c, cards)) return true;
      num_cards++;
      c.used = false;
      rank_count[c.rank]++;
      color_count[c.color]++;
    }
  }

  return false;
}

int main() {
  std::ios_base::sync_with_stdio(false);
  int n;
  while (std::cin >> n) {
      std::vector<card> cards;
      rank_count.clear();
      color_count.clear();
      std::string tmp;
      for (int i=0; i<n; ++i) {
          std::cin >> tmp;
          auto color = tmp[1];
          auto rank = tmp[0];
          color_count[color]++;
          rank_count[rank]++;
          cards.push_back({rank, color, false});
        }

        num_cards = n;
        if (try_next({0, 0, true}, cards)){
            std::cout << "YES\n";        
        } else {
            std::cout << "NO\n";
        }
  }

  return 0;
}