from collections import deque
H,W = map(int,input().split())
sx,sy,gx,gy = map(int,input().split())
B = [[0 for _ in range(W+1)]]
for _ in range(H):
    b = [0]+list(map(int,list(input())))
    B.append(b)
A = [[0 for _ in range(W+1)] for _ in range(H+1)]
A[sx][sy] = 1
que = deque([(sx,sy)])
while que:
    i,j = que.popleft()
    for di,dj in [(1,0),(0,1),(-1,0),(0,-1)]:
        ni = i+di
        nj = j+dj
        if 1<=ni<=H and 1<=nj<=W and abs(B[ni][nj]-B[i][j])<=1 and A[ni][nj]==0:
            A[ni][nj] = 1
            que.append((ni,nj))
    for di,dj in [(2,0),(0,2),(-2,0),(0,-2)]:
        ni = i+di
        nj = j+dj
        if 1<=ni<=H and 1<=nj<=W and B[ni][nj]==B[i][j] and B[i+di//2][j+dj//2]<B[i][j] and A[ni][nj]==0:
            A[ni][nj] = 1
            que.append((ni,nj))
if A[gx][gy]==1:
    print("YES")
else:
    print("NO")