def read_data():
    N, M = map(int, input().split())
    A = [input() for n in range(N)]
    return N, M, A


def solve(N0, M0, A):
    global Af, ns, ms, N, M
    N = N0 + 2
    M = M0 + 2
    n_dots = sum(row.count('.') for row in A)
    Af = [[True] * M]
    Af.extend([[True] + [c == '#' for c in row] + [True] for row in A])
    Af.append([True] * M)
    for ns in range(1, N - 1):
        for ms in range(1, M - 1):
            if Af[ns][ms]:
                continue
            Af[ns][ms] = True
            for dn, dm in [(1, 0), (-1, 0), (0, 1), (0, -1)]:
                n = ns + dn
                m = ms + dm
                if Af[n][m]:
                    continue
                Af[n][m] = True
                if dfs(n, m, dn, dm, n_dots - 2):
                    return True
                Af[n][m] = False
            Af[ns][ms] = False
    return False


def dfs(n, m, dn, dm, k):
    global Af, ns, ms, N, M
    if k == 0:
        if n + dn == ns and m + dm == ms:
            return True
        elif n - dm == ns and m + dn == ms:
            return True
        else:
            return False
    if Af[n + dn][m + dm]:
        dn, dm = -dm, dn  # 左90°回転
        if Af[n + dn][m + dm]:
            return False
    nn = n + dn
    mm = m + dm
    Af[nn][mm] = True
    result = dfs(nn, mm, dn, dm, k-1)
    Af[nn][mm] = False
    return result


if __name__ == '__main__':
    N, M, A = read_data()
    if solve(N, M, A):
        print('YES')
    else:
        print('NO')