import sys

a = sys.stdin.readline().split(' ')
data = sys.stdin.readlines()

S = int(a[0])
H = int(a[1])

dx = [0,1,0,-1]
dy = [1,0,-1,0]

ans = 'Yes'
if S == 1 and H == 1:
    ans = 'Yes'
else:
    for i in range(S):
        for j in range(H):
            if data[i][j] == '.':
                continue
            else:
                for k in range(4):
                    x = j + dx[k]
                    y = i + dy[k]
                    if x < 0 or y < 0 or x >= H or y >= S:
                        continue
                    else:
                        if data[y][x] == "#":
                            ans = 'Yes'
                            break
                        else:
                            ans = 'No'
                            continue

print(ans)

