#yuki424
import Queue

h,w = map(int, raw_input().split())
sx,sy,gx,gy = map(int, raw_input().split())
sx,sy,gx,gy=sx-1,sy-1,gx-1,gy-1
l=[]
for i in xrange(h):
 l.append(map(int,list(raw_input())))
ls = [[True for i in range(w)] for j in range(h)]
q = Queue.Queue()
q.put((sx,sy))
ls[sx][sy] = False
f = False
while not q.empty():
    x,y = q.get()
    if x == gx and y == gy:
        f = True
        break;
    for dx,dy in [(-1,0),(1,0),(0,-1),(0,1)]:
        if 0 <= x+dx and x+dx < h and 0 <= y+dy and y+dy < w and ls[x+dx][y+dy] and abs(l[x][y] - l[x+dx][y+dy]) < 2:
            q.put((x+dx,y+dy))
            ls[x+dx][y+dy] = False
    for dx,dy in [(-2,0),(2,0),(0,-2),(0,2)]:
        if 0 <= x+dx and x+dx < h and 0 <= y+dy and y+dy < w and ls[x+dx][y+dy] and l[x][y] == l[x+dx][y+dy] and l[x+dx/2][y+dy/2] < l[x][y]:
            q.put((x+dx,y+dy))
            ls[x+dx][y+dy] = False
if f:
    print 'YES'
else:
    print 'NO'