
def main():
    x, y = [int(i) for i in input().split()]
    a = []
    for i in range(y):
        a.append(input().strip())

    for i in range(x):
        for j in range(y):
            f = False
            if a[j][i] == '#':
                if i-1 > 0 and a[j][i-1] == '#':
                    f = True
                if i+1 < x and a[j][i+1] == '#':
                    f = True
                if j-1 > 0 and a[j-1][i] == '#':
                    f = True
                if j+1 < y and a[j+1][i] == '#':
                    f = True

                if not f:
                    print('No')
                    return

    print('Yes')

if __name__ == '__main__':
    main()
