//1181floyd传递包
#include <iostream>
using namespace std;
/***********************************************/
bool graph[26][26];
void floyd()
{
    int i,j,k;
    for(k=0;k<26;k++)
    {
        for(i=0;i<26;i++)
        {
            for(j=0;j<26;j++)
            {
                if(graph[i][k]&&graph[k][j])
                    graph[i][j]=1;

            }
        }
    }
}
/************************************************/
int main()
{
    memset(graph,0,sizeof(graph));
    char ch[80];
    int a,b;
    while(cin>>ch)
    {
        if(ch[0]=='0')
        {
            floyd();
            if(graph[1][12])
                cout<<"Yes."<<endl;
            else cout<<"No."<<endl;
            memset(graph,0,sizeof(graph));
        }
        else
        {
            a=ch[0]-'a';
            int j=strlen(ch);
            b=ch[j-1]-'a';
            graph[a][b]=1;
        }

    }
    return 0;
}