a,b = map(int,input().split())
c=[list(map(str,list(input()))) for i in range(b)]
x=a
y=b
e=0
r=0
if y>1 or x>1:
    for i in range(0,y,2):
        for j in range(1,x,2):

            if c[i][j] == "#":
                e+=2
                if i > 0 and i < x-1 and j >0 and j < y-1:
                    if c[i+1][j]=="#" or c[i][j+1]=="#" or c[i-1][j]=="#" or c[i][j-1]=="#" :
                        r+=2

                elif i==0 and j!= 0 and j != y-1 :
                    if c[i+1][j]=="#" or c[i][j+1]=="#" or c[i][j-1]=="#" :
                        r+=2

                elif i == x-1 and j != 0 and j != y-1 :
                    if c[i][j+1] == "#" or c[i-1][j] == "#" or c[i][j-1] == "#" :
                        r+=2

                elif j == 0 and i != 0 and i != y-1:
                    if c[i+1][j] == "#" or c[i][j+1] == "#" or c[i-1][j] == "#" :
                        r+=2

                elif j == y-1 and i != y-1 and i != 0:
                    if c[i+1][j] == "#" or c[i-1][j] == "#" or c[i][j-1] == "#" :
                        r+=2

                elif i==0 and j == 0:
                    if c[i+1][j]=="#" or c[i][j+1]=="#" :
                        r+=1

                elif i==0 and j == y-1:
                    if c[i+1][j]=="#"  or c[i][j-1]=="#" :
                        r+=2

                elif i==x-1 and j == 0:
                    if c[i][j+1]=="#" or c[i-1][j]=="#" :
                        r+=2

                elif i == x-1 and j == y-1:
                    if c[i-1][j]=="#" or c[i][j-1]=="#" :
                        r+=2
elif y==1 :
    for i in range(0,x,2):
        if c[0][i] == "#":
            e+=2
            print(i)
            if i < x-1 :
                if c[0][i+1]=="#" :
                    r+=2
elif x==1 :
    for i in range(0,y,2):
        if c[i][0] == "#":
            e+=2
            if i < y-1 :
                if c[i+1][0]=="#" :
                    r+=2
if r==e and r!=0:
    print("Yes")
else :
    print("No")
