H,W=map(int,input().split())
s = [list(input()) for i in range(H)]

flag=True
if H==W==1:
    if s[0][0]=='#':
        flag=False
elif H>=2 and W==1:
    for i in range(H):
        if s[i][0] == '#':
            if i==0:
                if s[i+1][0]=='.':
                    flag=False
                    break
                else:
                    continue
            elif i==H-1:
                if s[i-1][0]=='.':
                    flag=False
                    break
                else:
                    continue
            else:
                if s[i+1][0]==s[i-1][0]=='.':
                    flag=False
                    break
                else:
                    continue
        else:
            continue
elif H==1 and W>=2:
    for i in range(W):
        if s[0][i]=='#':
            if i==0:
                if s[0][i+1]=='.':
                    flag=False
                    break
                else:
                    continue
            elif i==W-1:
                if s[0][i-1]=='.':
                    flag=False
                    break
                else:
                    continue
            else:
                if s[0][i+1]==s[0][i-1]=='.':
                    flag=False
                    break
                else:
                    continue
        else:
            continue
else:
    for i in range(H):
        if i==0:
            for j in range(W):
                if s[i][j]=='#':
                    if j==0:
                        if s[i][j+1]==s[i+1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                    elif j==W-1:
                        if s[i][j-1]==s[i+1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                    else:
                        if s[i][j+1]==s[i][j-1]==s[i+1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                else:
                    continue
            if flag==False:
                break
        elif i==H-1:
            for j in range(W):
                if s[i][j]=='#':
                    if j==0:
                        if s[i][j+1]==s[i-1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                    elif j==W-1:
                        if s[i][j-1]==s[i-1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                    else:
                        if s[i][j+1]==s[i][j-1]==s[i-1][j]=='.':
                            flag=False
                            break
                        else:
                            continue
                else:
                    continue
            if flag==False:
                break
        else:
            for j in range(W):
                if s[i][j]=='#':
                    if j==0:
                        if s[i-1][j]==s[i+1][j]==s[i][j+1]=='.':
                            flag=False
                            break
                        else:
                            continue
                    elif j==W-1:
                        if s[i-1][j]==s[i+1][j]==s[i][j-1]=='.':
                            flag=False
                            break
                        else:
                            continue
                    else:
                        if s[i-1][j]==s[i+1][j]==s[i][j-1]==s[i][j+1]=='.':
                            flag=False
                            break
                        else:
                            continue
                else:
                    continue
            if flag==False:
                break

if flag:
    print('Yes')
else:
    print('No')

Measured memory_bytes: 3192