H,W = map(int,input().split())
s = [input() for _ in range(H)]
if H==1 and W==1:
    print('No')
else:
    for i in range(H):
        for j in range(W):
            if s[i][j] == '#':
                if i-1>=0:
                    if s[i-1][j] == '#':break
                if i+1<H:
                    if s[i+1][j] == '#':break
                if j-1>=0:
                    if s[i][j-1] == '#':break
                if j+1<W:
                    if s[i][j+1] == '#':break
                print('No')
                exit(0)
    else:
        print('Yes')