H,W=map(int,input().split())
S=[]
for _ in range(H):
    S.append(input())
down=[[0]*(W+1) for _ in range(H+1)]
up=[[0]*(W+1) for _ in range(H+1)]
for i in range(H):
    for j in range(W):
        if S[i][j]=='#':
            down[i][j]+=1
            up[i][j]+=1
            if i!=H-1 and j!=W-1 and S[i+1][j+1]=='#':
                    down[i+1][j+1]+=down[i][j]
            if i!=H-1 and j!=0 and S[i+1][j-1]=='#':
                    up[i+1][j-1]+=up[i][j]
ansdown=[[0]*(W+1) for _ in range(H+1)]
ansup=[[0]*(W+1) for _ in range(H+1)]

for i in range(1,H-1):
    for j in range(1,W-1):
        if S[i][j]=='#' and S[i-1][j-1]=='#' and S[i-1][j+1]=='#' and S[i+1][j-1]=='#' and S[i+1][j+1]=='#':
            left,right=0,10**6//2+1
            while right-left>1:
                 mid=(right+left)//2
                 x=i+mid
                 y=j+mid
                 xs=i-mid-1
                 ys=j-mid-1
                 x2=i+mid
                 y2=j-mid
                 xs2=i-mid-1
                 ys2=j+mid+1
                 if 0<=x<H and 0<=y<W and 0<=xs+1<H and 0<=ys+1<W and down[x][y]-down[xs][ys]==mid*2+1:
                    if 0<=x2<H and 0<=y2<W and 0<=xs2+1<H and 0<=ys2-1<W and up[x2][y2]-up[xs2][ys2]==mid*2+1:
                        left=mid
                    else:
                        right=mid
                 else:
                      right=mid
                 mid=left
                 ansdown[i-mid][j-mid]+=1
                 ansdown[i+mid+1][j+mid+1]-=1
                 ansup[i-mid][j+mid]+=1
                 ansup[i+mid+1][j-mid-1]+=1
for i in range(H):
    for j in range(W):
        if i!=H-1 and j!=W-1 and S[i+1][j+1]=='#':
            ansdown[i+1][j+1]+=down[i][j]
        if i!=H-1 and j!=0 and S[i+1][j-1]=='#':
            ansup[i+1][j-1]+=up[i][j]
flag=True
for i in range(H):
     for j in range(W):
          if S[i][j]=='#':
               if ansdown[i][j]==0 and ansup[i][j]==0:
                    flag=False
#print(ansdown)
#print(ansup)
if flag:
     print('Yes')
else:
     print('No')