#include <stdio.h>
#include <iostream>
#include <vector>
#include <set>
#include <string>
#include <map>
#include <algorithm>

using namespace std;

int find_etalon(vector<string> arr){
    if(arr[0]==arr[1])
        return 0;
    if(arr[0]==arr[2])
        return 0;
    if(arr[1]==arr[2])
        return 1;
}




bool dfs(map<char,vector<char>> arr){
    vector<char> keys;
    for(auto el:arr)
        keys.push_back(el.first);
    int n = keys.size();
    bool ans = false;
    for(int k=0;k<1000;k++){
        for(auto el:arr){
            random_shuffle(el.second.begin(),el.second.end()); 
        }
        for(int lk=0;lk<5;lk++){
            random_shuffle(keys.begin(),keys.end());
            bool lcl = true;
            for(int i=0;i<n-1;i++){
                char sym = keys[i],sym2=keys[(i+1)];
                //lcl &= (arr[sym][arr[sym].size()-1]==arr[sym2][arr[sym2].size()-1]);
                bool l2cl = false;
                for(int h=0;h<arr[sym].size();h++){
                    for(int g=0;g<arr[sym].size();g++)
                    l2cl |= arr[sym][h]==arr[sym2][g];
                }
                lcl &= l2cl;
            }
            ans |= lcl;
            if(ans)
                return true;
        }
    }
    return ans;
}

int main(){
    //freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
    int n;
    while(cin>>n){
        map<char,vector<char>> suits, ranks;
        vector<string> arr;
        string s;
        for(int i=0;i<n;i++){
            cin >> s;
            arr.push_back(s);
            ranks[s[0]].push_back(s[1]);
            suits[s[1]].push_back(s[0]);
        }
        sort(arr.begin(),arr.end());
        string lol;
        for(int i=0;i<n;i++)
            lol+=arr[i];
        bool ans;
        string san;
        ans = dfs(suits);
        ans |= dfs(ranks);
        if(arr.size()==1)
            ans = true;
        san = (ans)?"YES":"NO";
        cout << san << endl;
    }
    return 0;
}