from typing import List N_MAX = 13 popcount = [0] * (1 << N_MAX) for S in range(1, 1 << N_MAX): popcount[S] = popcount[S & (S - 1)] + 1 def addeq_poly(f: List[int], g: List[int]): """ f += g """ for i, gi in enumerate(g): f[i] += gi def subeq_poly(f: List[int], g: List[int]): """ f -= g """ for i, gi in enumerate(g): f[i] -= gi def subset_zeta(f: List[int], n: int): """ Inplace conversion from f to ζf. ζf is defined as follows: (ζf)(S) = Σ[T⊆S] f(T) """ block = 1 while block < 1 << n: offset = 0 while offset < 1 << n: for p in range(offset, offset + block): f[p + block] += f[p] offset += 2 * block block <<= 1 def subset_zeta_poly(f: List[List[int]], n: int): """ Inplace conversion from f to ζf. ζf is defined as follows: (ζf)(S) = Σ[T⊆S] f(T) """ block = 1 while block < 1 << n: offset = 0 while offset < 1 << n: for p in range(offset, offset + block): addeq_poly(f[p + block], f[p]) offset += 2 * block block <<= 1 def subset_mobius_poly(f: List[List[int]], n: int): """ Inplace conversion from f to μf. μf is defined as follows: (μf)(S) = Σ[T⊆S] (-1)^(|S/T|) f(T) """ block = 1 while block < 1 << n: offset = 0 while offset < 1 << n: for p in range(offset, offset + block): subeq_poly(f[p + block], f[p]) offset += 2 * block block <<= 1 def mul_poly(f: List[int], g: List[int]): """ Returns h = fg mod x^n, where f, g are polynomials with degree n-1 defined as follows: f(x) = Σ_i f[i] x^i, g(x) = Σ_i g[i] x^i. """ n = len(f) h = [0] * n for i in range(n): for j in range(n - i): h[i + j] += f[i] * g[j] return h def ranked(f: List[int], n: int): """ Add rank """ return [[(i == popcount[S]) * f[S] for i in range(n + 1)] for S in range(1 << n)] def deranked(rf: List[List[int]], n: int): """ Remove rank """ return [rf[S][popcount[S]] for S in range(1 << n)] def subset_conv(f: List[int], g: List[int], n: int): rf = ranked(f, n) rg = ranked(g, n) subset_zeta_poly(rf, n) subset_zeta_poly(rg, n) for i in range(1 << n): rf[i] = mul_poly(rf[i], rg[i]) subset_mobius_poly(rf, n) return deranked(rf, n) def exp(f: List[int], n: int): """ Subset exp of Σ[S⊆{0,1,...,n-1}] f(S) """ assert f[0] == 0 g = [1] for i in range(n): g += subset_conv(g, f[1 << i: 1 << (i + 1)], i) return g def bit_deposit(src, mask): dst = 0 j = 0 for i in range(N_MAX): if (mask >> i) & 1: dst |= ((src >> j) & 1) << i j += 1 return dst def bit_extract(src, mask): dst = 0 j = 0 for i in range(N_MAX): if (mask >> i) & 1: dst |= ((src >> i) & 1) << j j += 1 return dst n, m = map(int, input().split()) edges = [] for _ in range(m): u, v = map(int, input().split()) u -= 1 v -= 1 edges.append((u, v)) # E[S] = # of edges connecting vertices in S E = [0] * (1 << n) for u, v in edges: E[(1 << u) | (1 << v)] += 1 subset_zeta(E, n) cycle = [0] * (1 << n) adj = [[] for _ in range(n)] for u, v in edges: adj[u].append(v) adj[v].append(u) cycle_dp = [[0] * n for _ in range(1 << n)] for v in range(n): cycle_dp[1 << v][v] = 1 for s in range(1, 1 << n): start = 0 while not ((s >> start) & 1): start += 1 for cur in range(n): if cycle_dp[s][cur] == 0: continue for nxt in adj[cur]: if start == nxt: cycle[s] += cycle_dp[s][cur] elif start < nxt and not ((s >> nxt) & 1): cycle_dp[s | (1 << nxt)][nxt] += cycle_dp[s][cur] for s in range(1, 1 << n): if popcount[s] == 1: cycle[s] = 1 elif popcount[s] == 2: cycle[s] = 0 else: cycle[s] //= 2 f = [0] for v in range(n): f += [0] * (1 << v) for X in range(1 << v, 1 << (v + 1)): mask = ((1 << (v + 1)) - 1) ^ X k = popcount[mask] g = [0] * (1 << k) for T in range(1 << k): S = bit_deposit(T, mask) g[T] = f[S] * (E[S | X] - E[S] - E[X]) exp_g = exp(g, k) for T in range(1 << k): S = bit_deposit(T, mask) f[S | X] += cycle[X] * exp_g[T] print(exp(f, n)[-1])