import sys

H, W = map(int, input().split())

A = []
for i in range(W):
    A.append(list(input()))

# print(A)
for r in range(H):
    for line in range(W):
        # print(r, line)
        if(A[r][line] != "#"):
            continue

        # print(r, line, A[r][line])

        if(line == 0):
            L = False
        else:
            L = A[r][line - 1] == "#"

        if(r == 0):
            U = False
        else:
            U = A[r - 1][line] == "#"

        if(line == W - 1):
            R = False
        else:
            R = A[r][line + 1] == "#"

        if(r == H - 1):
            D = False
        else:
            D = A[r + 1][line] == "#"

        # print(L, U, R, D)
        # print(L or U or R or D)
        if((L or U or R or D) is False):
            print("No")
            sys.exit()

print("Yes")