#include <cmath> #include <cstdio> #include <cstring> #include <iostream> #include <algorithm> using namespace std; inline int read() { int res = 0; bool bo = 0; char c; while (((c = getchar()) < '0' || c > '9') && c != '-'); if (c == '-') bo = 1; else res = c - 48; while ((c = getchar()) >= '0' && c <= '9') res = (res << 3) + (res << 1) + (c - 48); return bo ? ~res + 1 : res; } typedef long long ll; const int N = 20, M = 40; int n, m, ecnt, nxt[M], adj[N], go[M], tot, whi[N]; bool g[N][N], vis[N]; ll f[N][N], ans; inline void add_edge(const int &u, const int &v) { nxt[++ecnt] = adj[u]; adj[u] = ecnt; go[ecnt] = v; nxt[++ecnt] = adj[v]; adj[v] = ecnt; go[ecnt] = u; } inline void dfs(const int &u, const int &fu) { int i, j; for (int e = adj[u], v; e; e = nxt[e]) { if ((v = go[e]) == fu) continue; dfs(v, u); } for (i = 1; i <= tot; i++) { int x = whi[i]; f[u][x] = 1; for (int e = adj[u], v; e; e = nxt[e]) { if ((v = go[e]) == fu) continue; ll sum = 0; for (j = 1; j <= tot; j++) { int y = whi[j]; if (!g[x][y]) continue; sum += f[v][y]; } f[u][x] *= sum; } } } inline void solve() { int i; tot = 0; for (i = 1; i <= n; i++) if (vis[i]) whi[++tot] = i; dfs(1, 0); for (i = 1; i <= tot; i++) if (n - tot & 1) ans -= f[1][whi[i]]; else ans += f[1][whi[i]]; } inline void Dfs(const int &dep) { if (dep == n + 1) return solve(); vis[dep] = 0; Dfs(dep + 1); vis[dep] = 1; Dfs(dep + 1); } int main() { int i, x, y; n = read(); m = read(); for (i = 1; i <= m; i++) x = read(), y = read(), g[x][y] = g[y][x] = 1; for (i = 1; i < n; i++) x = read(), y = read(), add_edge(x, y); Dfs(1); cout << ans << endl; return 0; }