#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){
    /*if(ans)vector
        return true;
    if(st.size()==1)
        return true;
    set<char> paths = st[v];
    st.erase(v);
    for(auto i=paths.begin();i!=paths.end();i++){
        for(auto el: st){
            if(el.second.find(*i)!=el.second.end() && !visited[el.first]){
                map<char,set<char>> nst(st);
                if(el.second.size()>1)
                    nst[el.first].erase(*i);
                visited[el.first] = true; 
                //cout << v << el.first << " " << nst.size() <<endl;
                ans |= dfs(st,el.first);
            }
        }
    }
    return ans;*/
    vector<char> keys;
    for(auto el:arr)
        keys.push_back(el.first);
    int n = keys.size();
    bool ans = false;
    for(int k=0;k<5000;k++){
        for(auto el:arr){
            random_shuffle(el.second.begin(),el.second.end()); 
        }
        random_shuffle(keys.begin(),keys.end());
        for(int i=0;i<n-1;i++){
            char sym = keys[i],sym2=keys[i+1];
            ans |= (arr[sym][arr[sym].size()-1]==arr[sym2][arr[sym2].size()-1]);
        }
        if(ans)
            return true;
    }
    return false;
}

int main(){
    //freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
    int n;
    //string sut = "SHDC", rnk = "23456789AXJQK";
    //vector<>
    //for(int i=0;)
    map<string,string> rem;
    while(cin>>n){
        
        map<char,vector<char>> suits, ranks;
        vector<string> arr;
        for(int i=0;i<n;i++){
            string s;
            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;
        if(rem.find(lol)!=rem.end())
            san = rem[lol];
        else{
            ans = dfs(suits);
            san = (ans)?"YES":"NO";
            rem[lol] = san;
        }
        cout << san << endl;
    }
    return 0;
}