#include <iostream>
#include <queue>
#include <stdio.h>

using namespace std;

int main()
{
    int N;
    while(cin >> N){
    int matica[N][N];
    char farba[N], hodnota[N];
    for(int i = 0; i < N; i++){
        cin >> hodnota[i] >> farba[i];
    }
    for(int i = 0; i < N; i++){
        for(int j = 0; j < N; j++){
            if(farba[i] == farba[j] || hodnota[i] == hodnota[j]){
                matica[i][j] = 1;
            }else {
                matica[i][j] = 0;
            }
        }
    }
    int visited[N] = {0};
    queue<int> fronta;
    fronta.push(0);
    while(!fronta.empty()){
        int curr = fronta.front();
        fronta.pop();
        visited[curr] = 1;
        for(int i = 0; i < N; i++){
            if((matica[i][curr] == 1) && (visited[i] != 1)){
                fronta.push(i);
            }
        }
    }
    bool yes = true;
    for(int i = 0; i < N; i++){
        if(visited[i] == 0){
            yes = false;
        }
    }
    if (yes){
        printf("YES\n");
    }else{
        printf("NO\n");
    }


    }
    return 0;
}