#include <iostream>
using namespace std;
string t;
string s[100];
int c[26],d[26];
int main(void){
    for(int i=0;i<100;i++){
        cin>>s[i];
        if(s[i]==" ")cout<<"W"<<endl;
    }
    for(int i=0;i<100;i++){
        t+=s[i];
        t+='-';
    }
    //cout<<t<<endl;
    for(int i=0;i<100;i+=2){
        if(t[i]=='-')continue;
        else c[t[i]-'a']++;
    }
    for(int i=1;i<100;i+=2){
        if(t[i]=='-')continue;
        else d[t[i]-'a']++;
    }
    for(int i=0;i<26;i++){
        if(c[i]==0&&d[i]==0)continue;
        if(c[i]*d[i]==0){
            cout<<"Yes"<<endl;
            return 0;
        }
    }
    cout<<"NO"<<endl;
}