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#include<bits/stdc++.h>
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using namespace std;
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const int N=510;
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int H,W;
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char mp[N][N];
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int vis[N][N];
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int dx[4]={1,-1,0,0};
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int dy[4]={0,0,1,-1};
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bool flag=1;
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void dfs(int x,int y,char now_char)
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{
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	if(!flag)
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	{
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		return;
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	}
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	if(x==H&&y==W)
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	{
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		cout<<"Yes";
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		flag=0;
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		return;
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	}
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	if(now_char=='s')
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	{
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		now_char='n';
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	}
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	else if(now_char=='n')
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	{
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		now_char='u';
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	}
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	else if(now_char=='u')
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	{
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		now_char='k';
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	}
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	else if(now_char=='k')
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	{
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		now_char='e';
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	}
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	else if(now_char=='e')
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	{
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		now_char='s';
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	}
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	else
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	{
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		return;
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	}
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	for(int i=0;i<4;i++)
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	{
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		int xx=x+dx[i];
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		int yy=y+dy[i];
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		if(xx>0&&yy>0&&xx<=H&&yy<=W&&mp[xx][yy]==now_char&&vis[xx][yy]==0)
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		{
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			vis[xx][yy]=1;
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			dfs(xx,yy,now_char);
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			vis[xx][yy]=0;
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		}
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	}
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}
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int main()
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{
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	cin>>H>>W;
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	for(int i=1;i<=H;i++)
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	{
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		for(int j=1;j<=W;j++)
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		{
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			cin>>mp[i][j];
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		}
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	}
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    if(mp[1][1]!='s')
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    {
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        cout<<"No";
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        return 0;
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    }
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	dfs(1,1,mp[1][1]);
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	if(flag)
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	{
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		cout<<"No";
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	}
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	return 0;
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}