h,w = map(int, input().split())
bord = [list(input()) for n in range(w)]
Answer = 0
for y in range(len(bord)):
    for x in range(len(bord[0])):
        if bord[y][x]=='#':
            if y==0:
                if x==0:
                    if bord[y][x+1]=='#': Answer=1
                    if bord[y+1][x]=='#':Answer=1
                elif x==h-1:
                    if bord[y][x-1]=='#': Answer=1
                    if bord[y+1][x]=='#':Answer=1
                else:
                    if bord[y][x+1]=='#': Answer=1
                    if bord[y][x-1]=='#': Answer=1
                    if bord[y+1][x]=='#':Answer=1
            elif y==w-1:
                if x==0:
                    if bord[y][x+1]=='#': Answer=1
                    if bord[y-1][x]=='#':Answer=1
                elif x==h-1:
                    if bord[y][x-1]=='#': Answer=1
                    if bord[y-1][x]=='#':Answer=1
                else:
                    if bord[y][x+1]=='#': Answer=1
                    if bord[y][x-1]=='#': Answer=1
                    if bord[y-1][x]=='#':Answer=1
            elif x==0:
                if bord[y+1][x]=='#':Answer=1
                if bord[y-1][x]=='#':Answer=1
                if bord[y][x+1]=='#': Answer=1
            elif x==h-1:
                if bord[y+1][x]=='#':Answer=1
                if bord[y-1][x]=='#':Answer=1
                if bord[y][x-1]=='#': Answer=1
            else:
                if bord[y+1][x]=='#':Answer=1
                if bord[y-1][x]=='#':Answer=1
                if bord[y][x-1]=='#': Answer=1
                if bord[y][x+1]=='#': Answer=1
if Answer == 1:
    print('Yes')
else:
    print('No')


