H,W = map(int,input().split())
lis = ['.' +input()+'.' for _ in range(H)]
lis.insert(0,'.'*W)
lis.append('.'*W)
for i in range(1,H+1):
    for j in range(1,W+1):
        if lis[i][j] == '#':
            if lis[i+1][j]=='#' or lis[i-1][j]=='#' or lis[i][j+1]=='#' or lis[i][j-1] == '#':
                continue
            else:
                print('No')
                exit()
print('Yes')