h,w=gets.split.map(&:to_i)
sx,sy,gx,gy=gets.split.map{|s|s.to_i-1}
maze=h.times.map{gets.chomp.bytes.to_a}

init_state=[sx,sy]
q=[init_state]
visited={}

until q.empty?
	curr_state=q.shift
	next if visited[curr_state]
	visited[curr_state]=true
	if curr_state==[gx,gy]
		puts "YES"
		exit
	end
	height=maze.dig(*curr_state)
	x,y=curr_state

	[[1,0],[0,1],[-1,0],[0,-1]].each{|dx,dy|
		nx,ny=x+dx,y+dy
		next unless (0...h)===nx
		next unless (0...w)===ny
		next_state=[nx,ny]
		next if (maze.dig(*next_state)-height).abs>1
		q.push next_state
	}

	[[2,0],[0,2],[-2,0],[0,-2]].each{|dx,dy|
		nx,ny=x+dx,y+dy
		next unless (0...h)===nx
		next unless (0...w)===ny
		next_state=[nx,ny]
		next unless maze.dig(*next_state)==height
		middle=[x+dx/2,y+dy/2]
		next if maze.dig(*middle)>=height
		q.push next_state
	}	
end

puts "NO"