h,w = map(int,input().split())
s = [input() for _ in range(h)]
for i in range(h):
    for j in range(w):
        if s[i][j]=='#':
            if s[i-1][j]=='#' or s[i+1][j]=='#' or s[i][j-1]=='#' or s[i][j+1]=='#':
                continue
            else:
                print('No')
                exit()
print('Yes')