h,w = map(int,input().split()); s = []
for _ in range(h): s += [v=="#" for v in input()]
lurd = s[:]
for i in range(h-1):
    for j in range(w-1):
        lurd[w*(i+1)+(j+1)] += lurd[w*i+j]
rdlu = s[:]
for i in range(h-1,0,-1):
    for j in range(w-1,0,-1):
        rdlu[w*(i-1)+(j-1)] += rdlu[w*i+j]
ruld = s[:]
for i in range(h-1):
    for j in range(w-1,0,-1):
        ruld[w*(i+1)+(j-1)] += ruld[w*i+j]
ldru = s[:]
for i in range(h-1,0,-1):
    for j in range(w-1):
        ldru[w*(i-1)+(j+1)] += ldru[w*i+j]
p1 = [0]*(h+1)*(w+1)
p2 = [0]*(h+1)*(w+1)
p3 = [0]*(h+1)*(w+1)
p4 = [0]*(h+1)*(w+1)
for i in range(1,h-1):
    for j in range(1,w-1):
        if s[w*i+j]==0: continue
        ac1 = 0; wa = min(h-i,w-j)
        while wa-ac1>1:
            wj = (ac1+wa)//2
            if lurd[w*(i+wj)+(j+wj)]-lurd[w*i+j]==wj: ac1 = wj
            else: wa = wj
        ac2 = 0; wa = min(i+1,j+1)
        while wa-ac2>1:
            wj = (ac2+wa)//2
            if rdlu[w*(i-wj)+(j-wj)]-rdlu[w*i+j]==wj: ac2 = wj
            else: wa = wj
        ac3 = 0; wa = min(h-i,j+1)
        while wa-ac3>1:
            wj = (ac3+wa)//2
            if ruld[w*(i+wj)+(j-wj)]-ruld[w*i+j]==wj: ac3 = wj
            else: wa = wj
        ac4 = 0; wa = min(i+1,w-j)
        while wa-ac4>1:
            wj = (ac4+wa)//2
            if ldru[w*(i-wj)+(j+wj)]-ldru[w*i+j]==wj: ac4 = wj
            else: wa = wj
        m = min(ac1,ac2,ac3,ac4)
        if m==0: continue
        p1[(w+1)*i+j] += 1; p1[(w+1)*(i+m+1)+(j+m+1)] -= 1
        p2[(w+1)*i+j] += 1; p2[(w+1)*(i-m-1)+(j-m-1)] -= 1
        p3[(w+1)*i+j] += 1; p3[(w+1)*(i+m+1)+(j-m-1)] -= 1
        p4[(w+1)*i+j] += 1; p4[(w+1)*(i-m-1)+(j+m+1)] -= 1
t = [False]*h*w
for i in range(h):
    for j in range(w):
        t[w*i+j] |= p1[(w+1)*i+j]>0
        p1[(w+1)*(i+1)+(j+1)] += p1[(w+1)*i+j]
for i in range(h-1,-1,-1):
    for j in range(w-1,-1,-1):
        t[w*i+j] |= p2[(w+1)*i+j]>0
        p2[(w+1)*(i-1)+(j-1)] += p2[(w+1)*i+j]
for i in range(h):
    for j in range(w-1,-1,-1):
        t[w*i+j] |= p3[(w+1)*i+j]>0
        p3[(w+1)*(i+1)+(j-1)] += p3[(w+1)*i+j]
for i in range(h-1,-1,-1):
    for j in range(w):
        t[w*i+j] |= p4[(w+1)*i+j]>0
        p4[(w+1)*(i-1)+(j+1)] += p4[(w+1)*i+j]
print("Yes" if s==t else "No")