#全てのますに対して
#もし#なら、四方の１つでも#ならok
#孤立まんがいたらアウト

H,W= map(int,input().split())
le = [input() for i in range(H)]
answer = [['0' for i in range(W)] for j in range(H)]

ass='Yes'
for i in range(0,H):
    for j in range(0,W):
        bool=False

        if le[i][j]!='#':
            continue
            
        if (i!=H-1):
            if(le[i+1][j]=='#'):
                bool=True


        if (i!=0):
            if(le[i-1][j]=='#'):
                bool=True
    
        if (j!=W-1):
            if(le[i][j+1]=='#'):
                bool=True

        if (j!=0):
            if(le[i][j-1]=='#'):
                bool=True

        if bool==False:
            ans="No"

print(ass)