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

D=[[10**18]*W for _ in range(H)]
for i in range(H):
    c=0
    for j in range(W):
        if i+j>=H:
            break
        if S[i+j][j]=='#':
            c+=1
        else:
            c=0
        D[i+j][j]=min(D[i+j][j],c)

for j in range(W):
    c=0
    for i in range(H):
        if i+j>=W:
            break
        if S[i][i+j]=='#':
            c+=1
        else:
            c=0
        D[i][i+j]=min(D[i][i+j],c)

for i in range(H):
    c=0
    for j in range(W):
        if i-j<0:
            break
        if S[i-j][W-j-1]=='#':
            c+=1
        else:
            c=0
        D[i-j][W-j-1]=min(D[i-j][W-j-1],c)

for j in range(W):
    c=0
    for i in range(H):
        if j-i<0:
            break
        if S[H-i-1][j-i]=='#':
            c+=1
        else:
            c=0
        D[H-i-1][j-i]=min(D[H-i-1][j-i],c)

for i in range(H):
    c=0
    for j in range(W):
        if i+j>=H:
            break
        if S[i+j][W-j-1]=='#':
            c+=1
        else:
            c=0
        D[i+j][W-j-1]=min(D[i+j][W-j-1],c)

for j in range(W):
    c=0
    for i in range(H):
        if i+j>=W:
            break
        if S[H-i-1][i+j]=='#':
            c+=1
        else:
            c=0
        D[H-i-1][i+j]=min(D[H-i-1][i+j],c)

for i in range(H):
    c=0
    for j in range(W):
        if i-j<0:
            break
        if S[i-j][j]=='#':
            c+=1
        else:
            c=0
        D[i-j][j]=min(D[i-j][j],c)

for j in range(W):
    c=0
    for i in range(H):
        if j-i<0:
            break
        if S[i][j-i]=='#':
            c+=1
        else:
            c=0
        D[i][j-i]=min(D[i][j-i],c)

for i in range(H):
    for j in range(W):
        if D[i][j]==1:
            D[i][j]=0

T=[['.']*W for _ in range(H)]

for i in range(H):
    c=0
    for j in range(W):
        if i+j>=H:
            break
        c=max(c,D[i+j][j])
        if c>0:
            T[i+j][j]='#'
            c-=1

for j in range(W):
    c=0
    for i in range(H):
        if i+j>=W:
            break
        c=max(c,D[i][i+j])
        if c>0:
            T[i][i+j]='#'
            c-=1

for i in range(H):
    c=0
    for j in range(W):
        if i-j<0:
            break
        c=max(c,D[i-j][W-j-1])
        if c>0:
            T[i-j][W-j-1]='#'
            c-=1

for j in range(W):
    c=0
    for i in range(H):
        if j-i<0:
            break
        c=max(c,D[H-i-1][j-i])
        if c>0:
            T[H-i-1][j-i]='#'
            c-=1

for i in range(H):
    c=0
    for j in range(W):
        if i+j>=H:
            break
        c=max(c,D[i+j][W-j-1])
        if c>0:
            T[i+j][W-j-1]='#'
            c-=1

for j in range(W):
    c=0
    for i in range(H):
        if i+j>=W:
            break
        c=max(c,D[H-i-1][i+j])
        if c>0:
            T[H-i-1][i+j]='#'
            c-=1

for i in range(H):
    c=0
    for j in range(W):
        if i-j<0:
            break
        c=max(c,D[i-j][j])
        if c>0:
            T[i-j][j]='#'
            c-=1

for j in range(W):
    c=0
    for i in range(H):
        if j-i<0:
            break
        c=max(c,D[i][j-i])
        if c>0:
            T[i][j-i]='#'
            c-=1

if S==T:
    print('Yes')
else:
    print('No')