H,W = map(int,input().split())
sh,sw,gh,gw = map(int,input().split())
INF = float("inf")
maze = [[INF]*(W+2)]
memo = [[1 for i in range(W+2)]for j in range(H+2)]

def search(stack):
    lst = []
    for j in stack:
        h,w = j[0],j[1]
        if h==gh and w==gw:
            print("YES")
            exit(0)
        now = maze[h][w]
        for i in [[1,0],[0,1],[-1,0],[0,-1]]:
            nh,nw = h+i[0],w+i[1]
            if memo[nh][nw] and (maze[nh][nw]==now or maze[nh][nw]==now-1 or maze[nh][nw]==now+1):
                memo[nh][nw]=0
                lst.append([nh,nw])
            nnh,nnw = nh+i[0],nw+i[1]
            if nnh>=0 and nnh<=H and nnw>0 and nnw<=W:
                if maze[nh][nw]<now and maze[nnh][nnw]==now and memo[nnh][nnw]:
                    memo[nnh][nnw]=0
                    lst.append([nnh,nnw])
    return lst

for i in range(H):
    l = list(input())
    l = map(int,l)
    maze.append([INF]+list(l)+[INF])
maze.append([INF]*(W+2))

memo[sh][sw]=0
lst = search([[sh,sw]])
while lst!=[]:
    lst = search(lst)

print("NO")