#include <stdio.h>
#include <string.h>
#define MAX 55

bool map[MAX][MAX] ;
int n, m;

bool judge(int i , int j)
{
	if(i+1<n && j+1<m)
	{
		if(map[i][j] && map[i+1][j] && map[i][j+1] && map[i+1][j+1])
		{
			return true ;
		}
	}
	return false ;
}

bool DFS()
{
	for(int i = 0 ; i < n ; ++i)
	{
		for(int j = 0 ; j < m ; ++j)
		{
			if(judge(i,j))
			{
				map[i][j] = map[i+1][j] = map[i][j+1] = map[i+1][j+1] = false ;
				if(!DFS())
				{
					map[i][j] = map[i+1][j] = map[i][j+1] = map[i+1][j+1] = true ;
					return true ;
				}
				map[i][j] = map[i+1][j] = map[i][j+1] = map[i+1][j+1] = true ;
			}
			
		}
	}
	return false ;
}

int main()
{
	while(~scanf("%d%d",&n,&m))
	{
		char line[100] ;
		for(int i = 0 ; i < n ; ++i)
		{
			scanf("%s",line) ;
			for(int j = 0 ; j < m ; ++j)
			{
				if(line[j] == '0')
					map[i][j] = true ;
				else
					map[i][j] = false ;
			}
		}
		if(DFS())
			puts("Yes") ;
		else
			puts("No")  ;
	} 
	return 0 ;
}