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'
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)

