#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cerr << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cerr<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 300010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 30;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
mt19937 rng; //use it by rng() % mod, shuffle(all(vec), rng)
///////////////////////////////////////////////////////////////////////////////////////////////////

ll fac[MAX_N], inv[MAX_N], fiv[MAX_N]; //fiv:inv(fac(i))

ll mod_pow(ll a, ll n) {
	if(n == 0) return 1;
	ll res = mod_pow(a, n / 2);
	if(n % 2 == 0) return res * res % mod;
	else return a * res % mod * res % mod;
}

ll invf(ll a) {
	return mod_pow(a, mod - 2);
}

void C_init(int n) {
	fac[0] = fac[1] = 1; inv[1] = 1;
	fiv[0] = fiv[1] = 1;
	rep(i, 2, n + 1) {
		fac[i] = fac[i - 1] * i % mod;
		inv[i] = mod - inv[mod % i] * (mod / i) % mod;
		fiv[i] = fiv[i - 1] * inv[i] % mod;
	}
}

ll C(int a, int b) { //assume a >= b
	if(a < b || a < 0 || b < 0) return 0;
	return fac[a] * fiv[b] % mod * fiv[a - b] % mod;
}

int N, M;
vector<pi> G[30];
int cmp[1 << 20];
int cnt[1 << 20];
ll cp[1 << 20], sp[1 << 20];

int dfs(int v, int p, int goal) {
	if(v == goal) return 0;
	int res = -1;
	rep(i, 0, sz(G[v])) {
		auto e = G[v][i];
		if(e.fst == p) continue;
		int tmp = dfs(e.fst, v, goal);
		if(tmp != -1) {
			if(res == -1) res = tmp | (1 << e.sec);
			else res |= tmp | (1 << e.sec);
		}
	}
	return res;
}

void solve() {
	cin >> N >> M;
	C_init(M + 100);
	rep(i, 0, N - 1) {
		int a, b; cin >> a >> b; a--; b--;
		G[a].pb(pi(b, i));
		G[b].pb(pi(a, i));
	}
	rep(i, N - 1, M) {
		int a, b; cin >> a >> b; a--; b--;
		int bit = dfs(a, -1, b);
		cmp[bit]++;
	}
	rep(i, 0, N - 1) {
		rep(bit, 0, (1 << (N - 1))) {
			if(bit & (1 << i)) cmp[bit] += cmp[bit ^ (1 << i)];
		}
	}
	rep(bit, 0, (1 << (N - 1))) {
		cnt[bit] = M - (N - 1) - cmp[((1 << (N - 1)) - 1) ^ bit] + __builtin_popcount(bit);
	}
	cp[0] = 1;
	rep(bit, 0, (1 << (N - 1))) {
		ll con = __builtin_popcount(bit);
		rep(i, 0, N - 1) {
			if(bit & (1 << i)) continue;
			int nbit = bit | (1 << i);
			ADD(cp[nbit], fac[cnt[nbit] - 1] * fiv[cnt[bit]] % mod * cp[bit] % mod);
			ADD(sp[nbit], fac[cnt[nbit] - 1] * fiv[cnt[bit]] % mod * cp[bit] % mod * (con + 1) % mod);
			ADD(sp[nbit], fac[cnt[nbit]] * fiv[cnt[bit] + 1] % mod * sp[bit] % mod);
		}
	}
	cout <<	sp[(1 << (N - 1)) - 1] << "\n";
}

uint32_t rd() {
	uint32_t res;
#ifdef __MINGW32__
	asm volatile("rdrand %0" :"=a"(res) ::"cc");
#else
	res = std::random_device()();
#endif
	return res;
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
    cerr << fixed;
	cerr.precision(6);
	rng.seed(rd());
#ifdef LOCAL
	//freopen("in.txt", "wt", stdout); //for tester
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
	return 0;
}



Measured memory_bytes: 26880