#include<bits/stdc++.h>

 using namespace std;

 typedef unsigned int ui;

 typedef long long ll;

 typedef unsigned long long ull;

 #define pf printf

 #define prime1 1e9+7

 #define prime2 1e9+9

 #define scand(x) scanf("%llf",&x)

 #define f(i,a,b) for(int i=a;i<=b;i++)

 #define scan(a) scanf("%d",&a)

 #define dbg(args) cout<<#args<<":"<<args<<endl;

 #define pb(i) push_back(i)

 #define ppb(x) pop_back(x)

 #define maxn 100005

 int m,t,tot;

 struct node{

     char st,ed;

 }n[maxn];

 char s[maxn];

 bool vis[maxn];

 bool dfs(char a)

 {

     if(a=='m')return true;

     f(i,,tot-)

     {

         if(n[i].st==a&&!vis[i])

         {

             vis[i]=true;

             if(dfs(n[i].ed))return true;

             vis[i]=false;

         }

     }

     return false;

 }

 int main()

 {

     std::ios::sync_with_stdio(false);

     while(scanf("%s",s)==)

     {

         if(strcmp(s,"")==)

         {

             if(dfs('b'))

             {

                 pf("Yes.\n");

             }

             else pf("No.\n");

             tot=;

             memset(vis,false,sizeof(vis));

             continue;

         }

         n[tot].st=s[];

         n[tot].ed=s[strlen(s)-];

         tot++;

     }

  }