#include <iostream>
#include <vector>
#include <bitset>
using namespace std;

template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) v += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator >> (istream &is, Fp<MOD>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

// 二項係数ライブラリ
template<class T> struct BiCoef {
    vector<T> fact_, inv_, finv_;
    constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        int MOD = fact_[0].getmod();
        for(int i = 2; i < n; i++){
            fact_[i] = fact_[i-1] * i;
            inv_[i] = -inv_[MOD%i] * (MOD/i);
            finv_[i] = finv_[i-1] * inv_[i];
        }
    }
    constexpr T com(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n-k];
    }
    constexpr T fact(int n) const noexcept {
        if (n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if (n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if (n < 0) return 0;
        return finv_[n];
    }
};

const int MAX = 201010;
const int MOD = 1000000007;
using mint = Fp<MOD>;

int N, M;
using pint = pair<int,int>;
using Graph = vector<vector<pint> >;
Graph G;

int dfs(int v, int p, int goal) {
    if (v == goal) return 0;
    int res = -1;
    for (auto e : G[v]) {
        if (e.first == p) continue;
        int tmp = dfs(e.first, v, goal);
        if (tmp != -1) {
            if (res == -1) res = tmp | (1<<e.second);
            else res |= tmp | (1<<e.second);
        }
    }
    return res;
}

int main() {
    BiCoef<mint> bc(MAX);
    
    // 入力と、MST 以外の辺が MST と作るサイクルたち
    cin >> N >> M;
    G.assign(N, vector<pint>());
    for (int i = 0; i < N-1; ++i) {
        int a, b; cin >> a >> b; --a, --b;
        G[a].push_back({b, i});
        G[b].push_back({a, i});
    }
    vector<int> cmp(1<<(N-1), 0);
    for (int i = N-1; i < M; ++i) {
        int a, b; cin >> a >> b; --a, --b;
        int S = dfs(a, -1, b);
        cmp[S]++;
    }

    // 高速ゼータ変換
    for (int i = 0; i < N-1; ++i)
        for (int bit = 0; bit < 1<<(N-1); ++bit)
            if (bit & (1<<i))
                cmp[bit] += cmp[bit ^ (1<<i)];
    vector<int> cnt(1<<(N-1), 0);
    for (int bit = 0; bit < 1<<(N-1); ++bit) {
        cnt[bit] = M-(N-1) - cmp[(1<<(N-1))-1 - bit] + __builtin_popcount(bit);
    }
    
    // DP
    vector<mint> cdp(1<<(N-1), 0), sdp(1<<(N-1), 0);
    cdp[0] = 1;
    for (int bit = 0; bit < 1<<(N-1); ++bit) {
        long long con = __builtin_popcount(bit);
        for (int i = 0; i < N-1; ++i) {
            if (bit & (1<<i)) continue;
            int nbit = bit | (1<<i);
            cdp[nbit] += bc.fact(cnt[nbit]-1) * bc.finv(cnt[bit]) * cdp[bit];
            sdp[nbit] += bc.fact(cnt[nbit]) * bc.finv(cnt[bit]+1) * sdp[bit]
                + bc.fact(cnt[nbit]-1) * bc.finv(cnt[bit]) * cdp[bit] * (con + 1);
        }
    }
    cout << sdp[(1<<(N-1)) - 1] << endl;
}


Measured memory_bytes: 17280