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