1 /*******************************
 2 
 3 Date    : 2015-12-08 21:36:48
 4 Author  : WQJ (1225234825@qq.com)
 5 Link    : http://www.cnblogs.com/a1225234/
 6 Name     : hdu 1181
 7 
 8 ********************************/
 9 #include <iostream>
10 #include <cstdio>
11 #include <algorithm>
12 #include <cmath>
13 #include <cstring>
14 #include <string>
15 #include <set>
16 #include <vector>
17 #include <queue>
18 #include <stack>
19 #define LL long long
20 using namespace std;
21 int k;
22 char ch[500][2];
23 char a[50];
24 bool flag;
25 bool vis[500];
26 void dfs(int n)
27 {
28     int i,j;
29     vis[n]=1;
30     if(ch[n][1]==‘m‘)
31     {
32         flag=1;
33         return;
34     }
35     for(i=0;i<k;i++)
36     {
37         if(ch[i][0]==ch[n][1])
38         {
39             if(vis[i])    continue;
40             dfs(i);
41             vis[i]=0;
42             if(flag)    return;
43         }
44     }
45     return;
46 }
47 int main()
48 {    
49     freopen("in.txt","r",stdin);
50     int i,j;
51     while(scanf("%s",ch[0])!=EOF)
52     {
53         int len=strlen(ch[0]);
54         ch[0][1]=ch[0][len-1];
55         for(i=1;;i++)
56         {
57             scanf("%s",a);
58             if(a[0]==‘0‘)
59                 break;
60             int len=strlen(a);
61             ch[i][0]=a[0];
62             ch[i][1]=a[len-1];
63         }
64         k=i+1;
65         flag=0;
66         memset(vis,0,sizeof(vis));
67         for(i=0;i<k;i++)
68         {
69             if(ch[i][0]==‘b‘)
70             {
71                 dfs(i);
72                 vis[i]=0;
73             }
74         }
75         printf("%s\n",flag?"Yes.":"No.");
76     }
77     return 0;
78 }