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